Asynchronous I/O (asyncio) — SQLAlchemy 2.0 Documentation

Release: 2.0.48 | Release Date: March 2, 2026

# SQLAlchemy 2.0 Documentation

# Asynchronous I/O (asyncio)

Support for Python asyncio. Support for Core and ORM usage is included, using asyncio-compatible dialects.

Added in version 1.4.

Warning

Please read Asyncio Platform Installation Notes (Including Apple M1) for important platform installation notes for many platforms, including Apple M1 Architecture.

See also

Asynchronous IO Support for Core and ORM - initial feature announcement

Asyncio Integration - example scripts illustrating working examples of Core and ORM use within the asyncio extension.

## Asyncio Platform Installation Notes (Including Apple M1)

The asyncio extension requires Python 3 only. It also depends upon the greenlet library. This dependency is installed by default on common machine platforms including:

    x86_64 aarch64 ppc64le amd64 win32

For the above platforms, `greenlet` is known to supply pre-built wheel files. For other platforms, greenlet does not install by default; the current file listing for greenlet can be seen at Greenlet - Download Files. Note that there are many architectures omitted, including Apple M1.

To install SQLAlchemy while ensuring the `greenlet` dependency is present regardless of what platform is in use, the `[asyncio]` setuptools extra may be installed as follows, which will include also instruct `pip` to install `greenlet`:

    pip install sqlalchemy[asyncio]

Note that installation of `greenlet` on platforms that do not have a pre-built wheel file means that `greenlet` will be built from source, which requires that Python’s development libraries also be present.

## Synopsis - Core

For Core use, the `create_async_engine()` function creates an instance of `AsyncEngine` which then offers an async version of the traditional `Engine` API. The `AsyncEngine` delivers an `AsyncConnection` via its `AsyncEngine.connect()` and `AsyncEngine.begin()` methods which both deliver asynchronous context managers. The `AsyncConnection` can then invoke statements using either the `AsyncConnection.execute()` method to deliver a buffered `Result`, or the `AsyncConnection.stream()` method to deliver a streaming server-side `AsyncResult`:

    >>> import asyncio

    >>> from sqlalchemy import Column
    >>> from sqlalchemy import MetaData
    >>> from sqlalchemy import select
    >>> from sqlalchemy import String
    >>> from sqlalchemy import Table
    >>> from sqlalchemy.ext.asyncio import create_async_engine

    >>> meta = MetaData()
    >>> t1 = Table("t1", meta, Column("name", String(50), primary_key=True))

    >>> async def async_main() -> None:
    ...     engine = create_async_engine("sqlite+aiosqlite://", echo=True)
    ...
    ...     async with engine.begin() as conn:
    ...         await conn.run_sync(meta.drop_all)
    ...         await conn.run_sync(meta.create_all)
    ...
    ...         await conn.execute(
    ...             t1.insert(), [{"name": "some name 1"}, {"name": "some name 2"}]
    ...         )
    ...
    ...     async with engine.connect() as conn:
    ...         # select a Result, which will be delivered with buffered
    ...         # results
    ...         result = await conn.execute(select(t1).where(t1.c.name == "some name 1"))
    ...
    ...         print(result.fetchall())
    ...
    ...     # for AsyncEngine created in function scope, close and
    ...     # clean-up pooled connections
    ...     await engine.dispose()

    >>> asyncio.run(async_main())
    BEGIN (implicit)
    ...
    CREATE TABLE t1 (
        name VARCHAR(50) NOT NULL,
        PRIMARY KEY (name)
    )
    ...
    INSERT INTO t1 (name) VALUES (?)
    [...] [('some name 1',), ('some name 2',)]
    COMMIT
    BEGIN (implicit)
    SELECT t1.name
    FROM t1
    WHERE t1.name = ?
    [...] ('some name 1',)
    [('some name 1',)]
    ROLLBACK

Above, the `AsyncConnection.run_sync()` method may be used to invoke special DDL functions such as `MetaData.create_all()` that don’t include an awaitable hook.

Tip

It’s advisable to invoke the `AsyncEngine.dispose()` method using `await` when using the `AsyncEngine` object in a scope that will go out of context and be garbage collected, as illustrated in the `async_main` function in the above example. This ensures that any connections held open by the connection pool will be properly disposed within an awaitable context. Unlike when using blocking IO, SQLAlchemy cannot properly dispose of these connections within methods like `__del__` or weakref finalizers as there is no opportunity to invoke `await`. Failing to explicitly dispose of the engine when it falls out of scope may result in warnings emitted to standard out resembling the form `RuntimeError: Event loop is closed` within garbage collection.

The `AsyncConnection` also features a “streaming” API via the `AsyncConnection.stream()` method that returns an `AsyncResult` object. This result object uses a server-side cursor and provides an async/await API, such as an async iterator:

    async with engine.connect() as conn:
        async_result = await conn.stream(select(t1))

        async for row in async_result:
            print("row: %s" % (row,))

## Synopsis - ORM

Using 2.0 style querying, the `AsyncSession` class provides full ORM functionality.

Within the default mode of use, special care must be taken to avoid lazy loading or other expired-attribute access involving ORM relationships and column attributes; the next section Preventing Implicit IO when Using AsyncSession details this.

Warning

A single instance of `AsyncSession` is not safe for use in multiple, concurrent tasks. See the sections Using AsyncSession with Concurrent Tasks and Is the Session thread-safe? Is AsyncSession safe to share in concurrent tasks? for background.

The example below illustrates a complete example including mapper and session configuration:

    >>> from __future__ import annotations

    >>> import asyncio
    >>> import datetime
    >>> from typing import List

    >>> from sqlalchemy import ForeignKey
    >>> from sqlalchemy import func
    >>> from sqlalchemy import select
    >>> from sqlalchemy.ext.asyncio import AsyncAttrs
    >>> from sqlalchemy.ext.asyncio import async_sessionmaker
    >>> from sqlalchemy.ext.asyncio import AsyncSession
    >>> from sqlalchemy.ext.asyncio import create_async_engine
    >>> from sqlalchemy.orm import DeclarativeBase
    >>> from sqlalchemy.orm import Mapped
    >>> from sqlalchemy.orm import mapped_column
    >>> from sqlalchemy.orm import relationship
    >>> from sqlalchemy.orm import selectinload

    >>> class Base(AsyncAttrs, DeclarativeBase):
    ...     pass

    >>> class B(Base):
    ...     __tablename__ = "b"
    ...
    ...     id: Mapped[int] = mapped_column(primary_key=True)
    ...     a_id: Mapped[int] = mapped_column(ForeignKey("a.id"))
    ...     data: Mapped[str]

    >>> class A(Base):
    ...     __tablename__ = "a"
    ...
    ...     id: Mapped[int] = mapped_column(primary_key=True)
    ...     data: Mapped[str]
    ...     create_date: Mapped[datetime.datetime] = mapped_column(server_default=func.now())
    ...     bs: Mapped[List[B]] = relationship()

    >>> async def insert_objects(async_session: async_sessionmaker[AsyncSession]) -> None:
    ...     async with async_session() as session:
    ...         async with session.begin():
    ...             session.add_all(
    ...                 [
    ...                     A(bs=[B(data="b1"), B(data="b2")], data="a1"),
    ...                     A(bs=[], data="a2"),
    ...                     A(bs=[B(data="b3"), B(data="b4")], data="a3"),
    ...                 ]
    ...             )

    >>> async def select_and_update_objects(
    ...     async_session: async_sessionmaker[AsyncSession],
    ... ) -> None:
    ...     async with async_session() as session:
    ...         stmt = select(A).order_by(A.id).options(selectinload(A.bs))
    ...
    ...         result = await session.execute(stmt)
    ...
    ...         for a in result.scalars():
    ...             print(a, a.data)
    ...             print(f"created at: {a.create_date}")
    ...             for b in a.bs:
    ...                 print(b, b.data)
    ...
    ...         result = await session.execute(select(A).order_by(A.id).limit(1))
    ...
    ...         a1 = result.scalars().one()
    ...
    ...         a1.data = "new data"
    ...
    ...         await session.commit()
    ...
    ...         # access attribute subsequent to commit; this is what
    ...         # expire_on_commit=False allows
    ...         print(a1.data)
    ...
    ...         # alternatively, AsyncAttrs may be used to access any attribute
    ...         # as an awaitable (new in 2.0.13)
    ...         for b1 in await a1.awaitable_attrs.bs:
    ...             print(b1, b1.data)

    >>> async def async_main() -> None:
    ...     engine = create_async_engine("sqlite+aiosqlite://", echo=True)
    ...
    ...     # async_sessionmaker: a factory for new AsyncSession objects.
    ...     # expire_on_commit - don't expire objects after transaction commit
    ...     async_session = async_sessionmaker(engine, expire_on_commit=False)
    ...
    ...     async with engine.begin() as conn:
    ...         await conn.run_sync(Base.metadata.create_all)
    ...
    ...     await insert_objects(async_session)
    ...     await select_and_update_objects(async_session)
    ...
    ...     # for AsyncEngine created in function scope, close and
    ...     # clean-up pooled connections
    ...     await engine.dispose()

    >>> asyncio.run(async_main())
    BEGIN (implicit)
    ...
    CREATE TABLE a (
        id INTEGER NOT NULL,
        data VARCHAR NOT NULL,
        create_date DATETIME DEFAULT CURRENT_TIMESTAMP NOT NULL,
        PRIMARY KEY (id)
    )
    ...
    CREATE TABLE b (
        id INTEGER NOT NULL,
        a_id INTEGER NOT NULL,
        data VARCHAR NOT NULL,
        PRIMARY KEY (id),
        FOREIGN KEY(a_id) REFERENCES a (id)
    )
    ...
    COMMIT
    BEGIN (implicit)
    INSERT INTO a (data) VALUES (?) RETURNING id, create_date
    [...] ('a1',)
    ...
    INSERT INTO b (a_id, data) VALUES (?, ?) RETURNING id
    [...] (1, 'b2')
    ...
    COMMIT
    BEGIN (implicit)
    SELECT a.id, a.data, a.create_date
    FROM a ORDER BY a.id
    [...] ()
    SELECT b.a_id AS b_a_id, b.id AS b_id, b.data AS b_data
    FROM b
    WHERE b.a_id IN (?, ?, ?)
    [...] (1, 2, 3)
    <A object at ...> a1
    created at: ...
    <B object at ...> b1
    <B object at ...> b2
    <A object at ...> a2
    created at: ...
    <A object at ...> a3
    created at: ...
    <B object at ...> b3
    <B object at ...> b4
    SELECT a.id, a.data, a.create_date
    FROM a ORDER BY a.id
    LIMIT ? OFFSET ?
    [...] (1, 0)
    UPDATE a SET data=? WHERE a.id = ?
    [...] ('new data', 1)
    COMMIT
    new data
    <B object at ...> b1
    <B object at ...> b2

In the example above, the `AsyncSession` is instantiated using the optional `async_sessionmaker` helper, which provides a factory for new `AsyncSession` objects with a fixed set of parameters, which here includes associating it with an `AsyncEngine` against particular database URL. It is then passed to other methods where it may be used in a Python asynchronous context manager (i.e. `async with:` statement) so that it is automatically closed at the end of the block; this is equivalent to calling the `AsyncSession.close()` method.

### Using AsyncSession with Concurrent Tasks

The `AsyncSession` object is a mutable, stateful object which represents a single, stateful database transaction in progress. Using concurrent tasks with asyncio, with APIs such as `asyncio.gather()` for example, should use a separate `AsyncSession` per individual task.

See the section Is the Session thread-safe? Is AsyncSession safe to share in concurrent tasks? for a general description of the `Session` and `AsyncSession` with regards to how they should be used with concurrent workloads.

### Preventing Implicit IO when Using AsyncSession

Using traditional asyncio, the application needs to avoid any points at which IO-on-attribute access may occur. Techniques that can be used to help this are below, many of which are illustrated in the preceding example.

- Attributes that are lazy-loading relationships, deferred columns or expressions, or are being accessed in expiration scenarios can take advantage of the `AsyncAttrs` mixin. This mixin, when added to a specific class or more generally to the Declarative `Base` superclass, provides an accessor `AsyncAttrs.awaitable_attrs` which delivers any attribute as an awaitable:

      from __future__ import annotations

      from typing import List

      from sqlalchemy.ext.asyncio import AsyncAttrs
      from sqlalchemy.orm import DeclarativeBase
      from sqlalchemy.orm import Mapped
      from sqlalchemy.orm import relationship

      class Base(AsyncAttrs, DeclarativeBase):
          pass

      class A(Base):
          __tablename__ = "a"

          # ... rest of mapping ...

          bs: Mapped[List[B]] = relationship()

      class B(Base):
          __tablename__ = "b"

          # ... rest of mapping ...

  Accessing the `A.bs` collection on newly loaded instances of `A` when eager loading is not in use will normally use lazy loading, which in order to succeed will usually emit IO to the database, which will fail under asyncio as no implicit IO is allowed. To access this attribute directly under asyncio without any prior loading operations, the attribute can be accessed as an awaitable by indicating the `AsyncAttrs.awaitable_attrs` prefix:

      a1 = (await session.scalars(select(A))).one()
      for b1 in await a1.awaitable_attrs.bs:
          print(b1)

  The `AsyncAttrs` mixin provides a succinct facade over the internal approach that’s also used by the `AsyncSession.run_sync()` method.

  Added in version 2.0.13.

  See also

  `AsyncAttrs`

- Collections can be replaced with write only collections that will never emit IO implicitly, by using the Write Only Relationships feature in SQLAlchemy 2.0. Using this feature, collections are never read from, only queried using explicit SQL calls. See the example `async_orm_writeonly.py` in the Asyncio Integration section for an example of write-only collections used with asyncio.

  When using write only collections, the program’s behavior is simple and easy to predict regarding collections. However, the downside is that there is not any built-in system for loading many of these collections all at once, which instead would need to be performed manually. Therefore, many of the bullets below address specific techniques when using traditional lazy-loaded relationships with asyncio, which requires more care.

- If not using `AsyncAttrs`, relationships can be declared with `lazy="raise"` so that by default they will not attempt to emit SQL. In order to load collections, eager loading would be used instead.

- The most useful eager loading strategy is the `selectinload()` eager loader, which is employed in the previous example in order to eagerly load the `A.bs` collection within the scope of the `await session.execute()` call:

      stmt = select(A).options(selectinload(A.bs))

- When constructing new objects, collections are always assigned a default, empty collection, such as a list in the above example:

      A(bs=[], data="a2")

  This allows the `.bs` collection on the above `A` object to be present and readable when the `A` object is flushed; otherwise, when the `A` is flushed, `.bs` would be unloaded and would raise an error on access.

- The `AsyncSession` is configured using `Session.expire_on_commit` set to False, so that we may access attributes on an object subsequent to a call to `AsyncSession.commit()`, as in the line at the end where we access an attribute:

      # create AsyncSession with expire_on_commit=False
      async_session = AsyncSession(engine, expire_on_commit=False)

      # sessionmaker version
      async_session = async_sessionmaker(engine, expire_on_commit=False)

      async with async_session() as session:
          result = await session.execute(select(A).order_by(A.id))

          a1 = result.scalars().first()

          # commit would normally expire all attributes
          await session.commit()

          # access attribute subsequent to commit; this is what
          # expire_on_commit=False allows
          print(a1.data)

Other guidelines include:

- Methods like `AsyncSession.expire()` should be avoided in favor of `AsyncSession.refresh()`; if expiration is absolutely needed. Expiration should generally not be needed as `Session.expire_on_commit` should normally be set to `False` when using asyncio.

- A lazy-loaded relationship can be loaded explicitly under asyncio using `AsyncSession.refresh()`, if the desired attribute name is passed explicitly to `Session.refresh.attribute_names`, e.g.:

      # assume a_obj is an A that has lazy loaded A.bs collection
      a_obj = await async_session.get(A, [1])

      # force the collection to load by naming it in attribute_names
      await async_session.refresh(a_obj, ["bs"])

      # collection is present
      print(f"bs collection: {a_obj.bs}")

  It’s of course preferable to use eager loading up front in order to have collections already set up without the need to lazy-load.

  Added in version 2.0.4: Added support for `AsyncSession.refresh()` and the underlying `Session.refresh()` method to force lazy-loaded relationships to load, if they are named explicitly in the `Session.refresh.attribute_names` parameter. In previous versions, the relationship would be silently skipped even if named in the parameter.

- Avoid using the `all` cascade option documented at Cascades in favor of listing out the desired cascade features explicitly. The `all` cascade option implies among others the refresh-expire setting, which means that the `AsyncSession.refresh()` method will expire the attributes on related objects, but not necessarily refresh those related objects assuming eager loading is not configured within the `relationship()`, leaving them in an expired state.

- Appropriate loader options should be employed for `deferred()` columns, if used at all, in addition to that of `relationship()` constructs as noted above. See Limiting which Columns Load with Column Deferral for background on deferred column loading.

- The “dynamic” relationship loader strategy described at Dynamic Relationship Loaders is not compatible by default with the asyncio approach. It can be used directly only if invoked within the `AsyncSession.run_sync()` method described at Running Synchronous Methods and Functions under asyncio, or by using its `.statement` attribute to obtain a normal select:

      user = await session.get(User, 42)
      addresses = (await session.scalars(user.addresses.statement)).all()
      stmt = user.addresses.statement.where(Address.email_address.startswith("patrick"))
      addresses_filter = (await session.scalars(stmt)).all()

  The write only technique, introduced in version 2.0 of SQLAlchemy, is fully compatible with asyncio and should be preferred.

  See also

  “Dynamic” relationship loaders superseded by “Write Only” - notes on migration to 2.0 style

- If using asyncio with a database that does not support RETURNING, such as MySQL 8, server default values such as generated timestamps will not be available on newly flushed objects unless the `Mapper.eager_defaults` option is used. In SQLAlchemy 2.0, this behavior is applied automatically to backends like PostgreSQL, SQLite and MariaDB which use RETURNING to fetch new values when rows are INSERTed.

### Running Synchronous Methods and Functions under asyncio

Deep Alchemy

This approach is essentially exposing publicly the mechanism by which SQLAlchemy is able to provide the asyncio interface in the first place. While there is no technical issue with doing so, overall the approach can probably be considered “controversial” as it works against some of the central philosophies of the asyncio programming model, which is essentially that any programming statement that can potentially result in IO being invoked must have an `await` call, lest the program does not make it explicitly clear every line at which IO may occur. This approach does not change that general idea, except that it allows a series of synchronous IO instructions to be exempted from this rule within the scope of a function call, essentially bundled up into a single awaitable.

As an alternative means of integrating traditional SQLAlchemy “lazy loading” within an asyncio event loop, an optional method known as `AsyncSession.run_sync()` is provided which will run any Python function inside of a greenlet, where traditional synchronous programming concepts will be translated to use `await` when they reach the database driver. A hypothetical approach here is an asyncio-oriented application can package up database-related methods into functions that are invoked using `AsyncSession.run_sync()`.

Altering the above example, if we didn’t use `selectinload()` for the `A.bs` collection, we could accomplish our treatment of these attribute accesses within a separate function:

    import asyncio

    from sqlalchemy import select
    from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine

    def fetch_and_update_objects(session):
        """run traditional sync-style ORM code in a function that will be
        invoked within an awaitable.

        """

        # the session object here is a traditional ORM Session.
        # all features are available here including legacy Query use.

        stmt = select(A)

        result = session.execute(stmt)
        for a1 in result.scalars():
            print(a1)

            # lazy loads
            for b1 in a1.bs:
                print(b1)

        # legacy Query use
        a1 = session.query(A).order_by(A.id).first()

        a1.data = "new data"

    async def async_main():
        engine = create_async_engine(
            "postgresql+asyncpg://scott:tiger@localhost/test",
            echo=True,
        )
        async with engine.begin() as conn:
            await conn.run_sync(Base.metadata.drop_all)
            await conn.run_sync(Base.metadata.create_all)

        async with AsyncSession(engine) as session:
            async with session.begin():
                session.add_all(
                    [
                        A(bs=[B(), B()], data="a1"),
                        A(bs=[B()], data="a2"),
                        A(bs=[B(), B()], data="a3"),
                    ]
                )

            await session.run_sync(fetch_and_update_objects)

            await session.commit()

        # for AsyncEngine created in function scope, close and
        # clean-up pooled connections
        await engine.dispose()

    asyncio.run(async_main())

The above approach of running certain functions within a “sync” runner has some parallels to an application that runs a SQLAlchemy application on top of an event-based programming library such as `gevent`. The differences are as follows:

1. unlike when using `gevent`, we can continue to use the standard Python asyncio event loop, or any custom event loop, without the need to integrate into the `gevent` event loop.

2. There is no “monkeypatching” whatsoever. The above example makes use of a real asyncio driver and the underlying SQLAlchemy connection pool is also using the Python built-in `asyncio.Queue` for pooling connections.

3. The program can freely switch between async/await code and contained functions that use sync code with virtually no performance penalty. There is no “thread executor” or any additional waiters or synchronization in use.

4. The underlying network drivers are also using pure Python asyncio concepts, no third party networking libraries as `gevent` and `eventlet` provides are in use.

## Using events with the asyncio extension

The SQLAlchemy event system is not directly exposed by the asyncio extension, meaning there is not yet an “async” version of a SQLAlchemy event handler.

However, as the asyncio extension surrounds the usual synchronous SQLAlchemy API, regular “synchronous” style event handlers are freely available as they would be if asyncio were not used.

As detailed below, there are two current strategies to register events given asyncio-facing APIs:

- Events can be registered at the instance level (e.g. a specific `AsyncEngine` instance) by associating the event with the `sync` attribute that refers to the proxied object. For example to register the `PoolEvents.connect()` event against an `AsyncEngine` instance, use its `AsyncEngine.sync_engine` attribute as target. Targets include:

  > `AsyncEngine.sync_engine`

  > `AsyncConnection.sync_connection`

  > `AsyncConnection.sync_engine`

  > `AsyncSession.sync_session`

- To register an event at the class level, targeting all instances of the same type (e.g. all `AsyncSession` instances), use the corresponding sync-style class. For example to register the `SessionEvents.before_commit()` event against the `AsyncSession` class, use the `Session` class as the target.

- To register at the `sessionmaker` level, combine an explicit `sessionmaker` with an `async_sessionmaker` using `async_sessionmaker.sync_session_class`, and associate events with the `sessionmaker`.

When working within an event handler that is within an asyncio context, objects like the `Connection` continue to work in their usual “synchronous” way without requiring `await` or `async` usage; when messages are ultimately received by the asyncio database adapter, the calling style is transparently adapted back into the asyncio calling style. For events that are passed a DBAPI level connection, such as `PoolEvents.connect()`, the object is a pep-249 compliant “connection” object which will adapt sync-style calls into the asyncio driver.

### Examples of Event Listeners with Async Engines / Sessions / Sessionmakers

Some examples of sync style event handlers associated with async-facing API constructs are illustrated below:

- Core Events on AsyncEngine

  In this example, we access the `AsyncEngine.sync_engine` attribute of `AsyncEngine` as the target for `ConnectionEvents` and `PoolEvents`:

      import asyncio

      from sqlalchemy import event
      from sqlalchemy import text
      from sqlalchemy.engine import Engine
      from sqlalchemy.ext.asyncio import create_async_engine

      engine = create_async_engine("postgresql+asyncpg://scott:tiger@localhost:5432/test")

      # connect event on instance of Engine
      @event.listens_for(engine.sync_engine, "connect")
      def my_on_connect(dbapi_con, connection_record):
          print("New DBAPI connection:", dbapi_con)
          cursor = dbapi_con.cursor()

          # sync style API use for adapted DBAPI connection / cursor
          cursor.execute("select 'execute from event'")
          print(cursor.fetchone()[0])

      # before_execute event on all Engine instances
      @event.listens_for(Engine, "before_execute")
      def my_before_execute(
          conn,
          clauseelement,
          multiparams,
          params,
          execution_options,
      ):
          print("before execute!")

      async def go():
          async with engine.connect() as conn:
              await conn.execute(text("select 1"))
          await engine.dispose()

      asyncio.run(go())

  Output:

      New DBAPI connection: <AdaptedConnection <asyncpg.connection.Connection object at 0x7f33f9b16960>>
      execute from event
      before execute!

- ORM Events on AsyncSession

  In this example, we access `AsyncSession.sync_session` as the target for `SessionEvents`:

      import asyncio

      from sqlalchemy import event
      from sqlalchemy import text
      from sqlalchemy.ext.asyncio import AsyncSession
      from sqlalchemy.ext.asyncio import create_async_engine
      from sqlalchemy.orm import Session

      engine = create_async_engine("postgresql+asyncpg://scott:tiger@localhost:5432/test")

      session = AsyncSession(engine)

      # before_commit event on instance of Session
      @event.listens_for(session.sync_session, "before_commit")
      def my_before_commit(session):
          print("before commit!")

          # sync style API use on Session
          connection = session.connection()

          # sync style API use on Connection
          result = connection.execute(text("select 'execute from event'"))
          print(result.first())

      # after_commit event on all Session instances
      @event.listens_for(Session, "after_commit")
      def my_after_commit(session):
          print("after commit!")

      async def go():
          await session.execute(text("select 1"))
          await session.commit()

          await session.close()
          await engine.dispose()

      asyncio.run(go())

  Output:

      before commit!
      execute from event
      after commit!

- ORM Events on async_sessionmaker

  For this use case, we make a `sessionmaker` as the event target, then assign it to the `async_sessionmaker` using the `async_sessionmaker.sync_session_class` parameter:

      import asyncio

      from sqlalchemy import event
      from sqlalchemy.ext.asyncio import async_sessionmaker
      from sqlalchemy.orm import sessionmaker

      sync_maker = sessionmaker()
      maker = async_sessionmaker(sync_session_class=sync_maker)

      @event.listens_for(sync_maker, "before_commit")
      def before_commit(session):
          print("before commit")

      async def main():
          async_session = maker()

          await async_session.commit()

      asyncio.run(main())

  Output:

      before commit

asyncio and events, two opposites

SQLAlchemy events by their nature take place within the interior of a particular SQLAlchemy process; that is, an event always occurs after some particular SQLAlchemy API has been invoked by end-user code, and before some other internal aspect of that API occurs.

Contrast this to the architecture of the asyncio extension, which takes place on the exterior of SQLAlchemy’s usual flow from end-user API to DBAPI function.

The flow of messaging may be visualized as follows:

     SQLAlchemy    SQLAlchemy        SQLAlchemy          SQLAlchemy   plain
      asyncio      asyncio           ORM/Core            asyncio      asyncio
      (public      (internal)                            (internal)
      facing)
    -------------|------------|------------------------|-----------|------------
    asyncio API  |            |                        |           |
    call  ->     |            |                        |           |
                 |  ->  ->    |                        |  ->  ->   |
                 |~~~~~~~~~~~~| sync API call ->       |~~~~~~~~~~~|
                 | asyncio    |  event hooks ->        | sync      |
                 | to         |   invoke action ->     | to        |
                 | sync       |    event hooks ->      | asyncio   |
                 | (greenlet) |     dialect ->         | (leave    |
                 |~~~~~~~~~~~~|      event hooks ->    | greenlet) |
                 |  ->  ->    |       sync adapted     |~~~~~~~~~~~|
                 |            |               DBAPI -> |  ->  ->   | asyncio
                 |            |                        |           | driver -> database

Where above, an API call always starts as asyncio, flows through the synchronous API, and ends as asyncio, before results are propagated through this same chain in the opposite direction. In between, the message is adapted first into sync-style API use, and then back out to async style. Event hooks then by their nature occur in the middle of the “sync-style API use”. From this it follows that the API presented within event hooks occurs inside the process by which asyncio API requests have been adapted to sync, and outgoing messages to the database API will be converted to asyncio transparently.

### Using awaitable-only driver methods in connection pool and other events

As discussed in the above section, event handlers such as those oriented around the `PoolEvents` event handlers receive a sync-style “DBAPI” connection, which is a wrapper object supplied by SQLAlchemy asyncio dialects to adapt the underlying asyncio “driver” connection into one that can be used by SQLAlchemy’s internals. A special use case arises when the user-defined implementation for such an event handler needs to make use of the ultimate “driver” connection directly, using awaitable only methods on that driver connection. One such example is the `.set_type_codec()` method supplied by the asyncpg driver.

To accommodate this use case, SQLAlchemy’s `AdaptedConnection` class provides a method `AdaptedConnection.run_async()` that allows an awaitable function to be invoked within the “synchronous” context of an event handler or other SQLAlchemy internal. This method is directly analogous to the `AsyncConnection.run_sync()` method that allows a sync-style method to run under async.

`AdaptedConnection.run_async()` should be passed a function that will accept the innermost “driver” connection as a single argument, and return an awaitable that will be invoked by the `AdaptedConnection.run_async()` method. The given function itself does not need to be declared as `async`; it’s perfectly fine for it to be a Python `lambda:`, as the return awaitable value will be invoked after being returned:

    from sqlalchemy import event
    from sqlalchemy.ext.asyncio import create_async_engine

    engine = create_async_engine(...)

    @event.listens_for(engine.sync_engine, "connect")
    def register_custom_types(dbapi_connection, *args):
        dbapi_connection.run_async(
            lambda connection: connection.set_type_codec(
                "MyCustomType",
                encoder,
                decoder,  # ...
            )
        )

Above, the object passed to the `register_custom_types` event handler is an instance of `AdaptedConnection`, which provides a DBAPI-like interface to an underlying async-only driver-level connection object. The `AdaptedConnection.run_async()` method then provides access to an awaitable environment where the underlying driver level connection may be acted upon.

Added in version 1.4.30.

## Using multiple asyncio event loops

An application that makes use of multiple event loops, for example in the uncommon case of combining asyncio with multithreading, should not share the same `AsyncEngine` with different event loops when using the default pool implementation.

If an `AsyncEngine` is be passed from one event loop to another, the method `AsyncEngine.dispose()` should be called before it’s reused on a new event loop. Failing to do so may lead to a `RuntimeError` along the lines of `Task <Task pending ...> got Future attached to a different loop`

If the same engine must be shared between different loop, it should be configured to disable pooling using `NullPool`, preventing the Engine from using any connection more than once:

    from sqlalchemy.ext.asyncio import create_async_engine
    from sqlalchemy.pool import NullPool

    engine = create_async_engine(
        "postgresql+asyncpg://user:pass@host/dbname",
        poolclass=NullPool,
    )

## Using asyncio scoped session

The “scoped session” pattern used in threaded SQLAlchemy with the `scoped_session` object is also available in asyncio, using an adapted version called `async_scoped_session`.

Tip

SQLAlchemy generally does not recommend the “scoped” pattern for new development as it relies upon mutable global state that must also be explicitly torn down when work within the thread or task is complete. Particularly when using asyncio, it’s likely a better idea to pass the `AsyncSession` directly to the awaitable functions that need it.

When using `async_scoped_session`, as there’s no “thread-local” concept in the asyncio context, the “scopefunc” parameter must be provided to the constructor. The example below illustrates using the `asyncio.current_task()` function for this purpose:

    from asyncio import current_task

    from sqlalchemy.ext.asyncio import (
        async_scoped_session,
        async_sessionmaker,
    )

    async_session_factory = async_sessionmaker(
        some_async_engine,
        expire_on_commit=False,
    )
    AsyncScopedSession = async_scoped_session(
        async_session_factory,
        scopefunc=current_task,
    )
    some_async_session = AsyncScopedSession()

Warning

The “scopefunc” used by `async_scoped_session` is invoked an arbitrary number of times within a task, once for each time the underlying `AsyncSession` is accessed. The function should therefore be idempotent and lightweight, and should not attempt to create or mutate any state, such as establishing callbacks, etc.

Warning

Using `current_task()` for the “key” in the scope requires that the `async_scoped_session.remove()` method is called from within the outermost awaitable, to ensure the key is removed from the registry when the task is complete, otherwise the task handle as well as the `AsyncSession` will remain in memory, essentially creating a memory leak. See the following example which illustrates the correct use of `async_scoped_session.remove()`.

`async_scoped_session` includes proxy behavior similar to that of `scoped_session`, which means it can be treated as a `AsyncSession` directly, keeping in mind that the usual `await` keywords are necessary, including for the `async_scoped_session.remove()` method:

    async def some_function(some_async_session, some_object):
        # use the AsyncSession directly
        some_async_session.add(some_object)

        # use the AsyncSession via the context-local proxy
        await AsyncScopedSession.commit()

        # "remove" the current proxied AsyncSession for the local context
        await AsyncScopedSession.remove()

Added in version 1.4.19.

## Using the Inspector to inspect schema objects

SQLAlchemy does not yet offer an asyncio version of the `Inspector` (introduced at Fine Grained Reflection with Inspector), however the existing interface may be used in an asyncio context by leveraging the `AsyncConnection.run_sync()` method of `AsyncConnection`:

    import asyncio

    from sqlalchemy import inspect
    from sqlalchemy.ext.asyncio import create_async_engine

    engine = create_async_engine("postgresql+asyncpg://scott:tiger@localhost/test")

    def use_inspector(conn):
        inspector = inspect(conn)
        # use the inspector
        print(inspector.get_view_names())
        # return any value to the caller
        return inspector.get_table_names()

    async def async_main():
        async with engine.connect() as conn:
            tables = await conn.run_sync(use_inspector)

    asyncio.run(async_main())

See also

Reflecting Database Objects

Runtime Inspection API

## Engine API Documentation

Object Name | Description
--- | ---
async_engine_from_config(configuration[, prefix], **kwargs) | Create a new AsyncEngine instance using a configuration dictionary.
AsyncConnection | An asyncio proxy for a `Connection`.
AsyncEngine | An asyncio proxy for a `Engine`.
AsyncTransaction | An asyncio proxy for a `Transaction`.
create_async_engine(url, **kw) | Create a new async engine instance.
create_async_pool_from_url(url, **kwargs) | Create a new async engine instance.

function sqlalchemy.ext.asyncio.create_async_engine(url: str | URL, **kw: Any) → AsyncEngine

  Create a new async engine instance.

  Arguments passed to `create_async_engine()` are mostly identical to those passed to the `create_engine()` function. The specified dialect must be an asyncio-compatible dialect such as asyncpg.

  Added in version 1.4.

  Parameters:

    async_creator –

    an async callable which returns a driver-level asyncio connection. If given, the function should take no arguments, and return a new asyncio connection from the underlying asyncio database driver; the connection will be wrapped in the appropriate structures to be used with the `AsyncEngine`. Note that the parameters specified in the URL are not applied here, and the creator function should use its own connection parameters.

    This parameter is the asyncio equivalent of the `create_engine.creator` parameter of the `create_engine()` function.

    Added in version 2.0.16.

function sqlalchemy.ext.asyncio.async_engine_from_config(configuration: Dict[str, Any], prefix: str = 'sqlalchemy.', **kwargs: Any) → AsyncEngine

  Create a new AsyncEngine instance using a configuration dictionary.

  This function is analogous to the `engine_from_config()` function in SQLAlchemy Core, except that the requested dialect must be an asyncio-compatible dialect such as asyncpg. The argument signature of the function is identical to that of `engine_from_config()`.

  Added in version 1.4.29.

function sqlalchemy.ext.asyncio.create_async_pool_from_url(url: str | URL, **kwargs: Any) → Pool

  Create a new async engine instance.

  Arguments passed to `create_async_pool_from_url()` are mostly identical to those passed to the `create_pool_from_url()` function. The specified dialect must be an asyncio-compatible dialect such as asyncpg.

  Added in version 2.0.10.

class sqlalchemy.ext.asyncio.AsyncEngine

  inherits from `sqlalchemy.ext.asyncio.base.ProxyComparable`, `sqlalchemy.ext.asyncio.AsyncConnectable`

  An asyncio proxy for a `Engine`.

  `AsyncEngine` is acquired using the `create_async_engine()` function:

      from sqlalchemy.ext.asyncio import create_async_engine

      engine = create_async_engine("postgresql+asyncpg://user:pass@host/dbname")

  Added in version 1.4.

  Member Name | Description
  --- | ---
  begin() | Return a context manager which when entered will deliver an `AsyncConnection` with an `AsyncTransaction` established.
  clear_compiled_cache() | Clear the compiled cache associated with the dialect.
  connect() | Return an `AsyncConnection` object.
  dispose() | Dispose of the connection pool used by this `AsyncEngine`.
  execution_options() | Return a new `AsyncEngine` that will provide `AsyncConnection` objects with the given execution options.
  get_execution_options() | Get the non-SQL options which will take effect during execution.
  raw_connection() | Return a “raw” DBAPI connection from the connection pool.
  sync_engine | Reference to the sync-style `Engine` this `AsyncEngine` proxies requests towards.
  update_execution_options() | Update the default execution_options dictionary of this `Engine`.

  method `sqlalchemy.ext.asyncio.AsyncEngine.` begin() → AsyncIterator[AsyncConnection]

    Return a context manager which when entered will deliver an `AsyncConnection` with an `AsyncTransaction` established.

    E.g.:

        async with async_engine.begin() as conn:
            await conn.execute(
                text("insert into table (x, y, z) values (1, 2, 3)")
            )
            await conn.execute(text("my_special_procedure(5)"))

  method `sqlalchemy.ext.asyncio.AsyncEngine.` clear_compiled_cache() → None

    Clear the compiled cache associated with the dialect.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

    This applies only to the built-in cache that is established via the `create_engine.query_cache_size` parameter. It will not impact any dictionary caches that were passed via the `Connection.execution_options.compiled_cache` parameter.

    Added in version 1.4.

  method `sqlalchemy.ext.asyncio.AsyncEngine.` connect() → AsyncConnection

    Return an `AsyncConnection` object.

    The `AsyncConnection` will procure a database connection from the underlying connection pool when it is entered as an async context manager:

        async with async_engine.connect() as conn:
            result = await conn.execute(select(user_table))

    The `AsyncConnection` may also be started outside of a context manager by invoking its `AsyncConnection.start()` method.

  property dialect: Dialect

    Proxy for the `Engine.dialect` attribute on behalf of the `AsyncEngine` class.

  method `sqlalchemy.ext.asyncio.AsyncEngine.` async dispose(close: bool = True) → None

    Dispose of the connection pool used by this `AsyncEngine`.

    Parameters:

      close –

      if left at its default of `True`, has the effect of fully closing all currently checked in database connections. Connections that are still checked out will not be closed, however they will no longer be associated with this `Engine`, so when they are closed individually, eventually the `Pool` which they are associated with will be garbage collected and they will be closed out fully, if not already closed on checkin.

      If set to `False`, the previous connection pool is de-referenced, and otherwise not touched in any way.

    See also

    `Engine.dispose()`

  property driver: Any

    Driver name of the `Dialect` in use by this `Engine`.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

  property echo: Any

    When `True`, enable log output for this element.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

    This has the effect of setting the Python logging level for the namespace of this element’s class and object reference. A value of boolean `True` indicates that the loglevel `logging.INFO` will be set for the logger, whereas the string value `debug` will set the loglevel to `logging.DEBUG`.

  property engine: Any

    Returns this `Engine`.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

    Used for legacy schemes that accept `Connection` / `Engine` objects within the same variable.

  method `sqlalchemy.ext.asyncio.AsyncEngine.` execution_options(**opt: Any) → AsyncEngine

    Return a new `AsyncEngine` that will provide `AsyncConnection` objects with the given execution options.

    Proxied from `Engine.execution_options()`. See that method for details.

  method `sqlalchemy.ext.asyncio.AsyncEngine.` get_execution_options() → _ExecuteOptions

    Get the non-SQL options which will take effect during execution.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

    See also

    `Engine.execution_options()`

  property name: Any

    String name of the `Dialect` in use by this `Engine`.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

  property pool: Pool

    Proxy for the `Engine.pool` attribute on behalf of the `AsyncEngine` class.

  method `sqlalchemy.ext.asyncio.AsyncEngine.` async raw_connection() → PoolProxiedConnection

    Return a “raw” DBAPI connection from the connection pool.

    See also

    Working with Driver SQL and Raw DBAPI Connections

  attribute `sqlalchemy.ext.asyncio.AsyncEngine.` sync_engine: Engine

    Reference to the sync-style `Engine` this `AsyncEngine` proxies requests towards.

    This instance can be used as an event target.

    See also

    Using events with the asyncio extension

  method `sqlalchemy.ext.asyncio.AsyncEngine.` update_execution_options(**opt: Any) → None

    Update the default execution_options dictionary of this `Engine`.

    Proxied for the `Engine` class on behalf of the `AsyncEngine` class.

    The given keys/values in **opt are added to the default execution options that will be used for all connections. The initial contents of this dictionary can be sent via the `execution_options` parameter to `create_engine()`.

    See also

    `Connection.execution_options()`

    `Engine.execution_options()`

  property url: URL

    Proxy for the `Engine.url` attribute on behalf of the `AsyncEngine` class.

class sqlalchemy.ext.asyncio.AsyncConnection

  inherits from `sqlalchemy.ext.asyncio.base.ProxyComparable`, `sqlalchemy.ext.asyncio.base.StartableContext`, `sqlalchemy.ext.asyncio.AsyncConnectable`

  An asyncio proxy for a `Connection`.

  `AsyncConnection` is acquired using the `AsyncEngine.connect()` method of `AsyncEngine`:

      from sqlalchemy.ext.asyncio import create_async_engine

      engine = create_async_engine("postgresql+asyncpg://user:pass@host/dbname")

      async with engine.connect() as conn:
          result = await conn.execute(select(table))

  Added in version 1.4.

  Member Name | Description
  --- | ---
  aclose() | A synonym for `AsyncConnection.close()`.
  begin() | Begin a transaction prior to autobegin occurring.
  begin_nested() | Begin a nested transaction and return a transaction handle.
  close() | Close this `AsyncConnection`.
  commit() | Commit the transaction that is currently in progress.
  exec_driver_sql() | Executes a driver-level SQL string and return buffered `Result`.
  execute() | Executes a SQL statement construct and return a buffered `Result`.
  execution_options() | Set non-SQL options for the connection which take effect during execution.
  get_nested_transaction() | Return an `AsyncTransaction` representing the current nested (savepoint) transaction, if any.
  get_raw_connection() | Return the pooled DBAPI-level connection in use by this `AsyncConnection`.
  get_transaction() | Return an `AsyncTransaction` representing the current transaction, if any.
  in_nested_transaction() | Return True if a transaction is in progress.
  in_transaction() | Return True if a transaction is in progress.
  info | Return the `Connection.info` dictionary of the underlying `Connection`.
  invalidate() | Invalidate the underlying DBAPI connection associated with this `Connection`.
  rollback() | Roll back the transaction that is currently in progress.
  run_sync() | Invoke the given synchronous (i.e. not async) callable, passing a synchronous-style `Connection` as the first argument.
  scalar() | Executes a SQL statement construct and returns a scalar object.
  scalars() | Executes a SQL statement construct and returns a scalar objects.
  start() | Start this `AsyncConnection` object’s context outside of using a Python `with:` block.
  stream() | Execute a statement and return an awaitable yielding a `AsyncResult` object.
  stream_scalars() | Execute a statement and return an awaitable yielding a `AsyncScalarResult` object.
  sync_connection | Reference to the sync-style `Connection` this `AsyncConnection` proxies requests towards.
  sync_engine | Reference to the sync-style `Engine` this `AsyncConnection` is associated with via its underlying `Connection`.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async aclose() → None

    A synonym for `AsyncConnection.close()`.

    The `AsyncConnection.aclose()` name is specifically to support the Python standard library `@contextlib.aclosing` context manager function.

    Added in version 2.0.20.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` begin() → AsyncTransaction

    Begin a transaction prior to autobegin occurring.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` begin_nested() → AsyncTransaction

    Begin a nested transaction and return a transaction handle.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async close() → None

    Close this `AsyncConnection`.

    This has the effect of also rolling back the transaction if one is in place.

  property closed: Any

    Return True if this connection is closed.

    Proxied for the `Connection` class on behalf of the `AsyncConnection` class.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async commit() → None

    Commit the transaction that is currently in progress.

    This method commits the current transaction if one has been started. If no transaction was started, the method has no effect, assuming the connection is in a non-invalidated state.

    A transaction is begun on a `Connection` automatically whenever a statement is first executed, or when the `Connection.begin()` method is called.

  property connection: NoReturn

    Not implemented for async; call `AsyncConnection.get_raw_connection()`.

  property default_isolation_level: Any

    The initial-connection time isolation level associated with the `Dialect` in use.

    Proxied for the `Connection` class on behalf of the `AsyncConnection` class.

    This value is independent of the `Connection.execution_options.isolation_level` and `Engine.execution_options.isolation_level` execution options, and is determined by the `Dialect` when the first connection is created, by performing a SQL query against the database for the current isolation level before any additional commands have been emitted.

    Calling this accessor does not invoke any new SQL queries.

    See also

    `Connection.get_isolation_level()` - view current actual isolation level

    `create_engine.isolation_level` - set per `Engine` isolation level

    `Connection.execution_options.isolation_level` - set per `Connection` isolation level

  property dialect: Dialect

    Proxy for the `Connection.dialect` attribute on behalf of the `AsyncConnection` class.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async exec_driver_sql(statement: str, parameters: _DBAPIAnyExecuteParams | None = None, execution_options: CoreExecuteOptionsParameter | None = None) → CursorResult[Any]

    Executes a driver-level SQL string and return buffered `Result`.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async execute(statement: Executable, parameters: _CoreAnyExecuteParams | None = None, *, execution_options: CoreExecuteOptionsParameter | None = None) → CursorResult[Any]

    Executes a SQL statement construct and return a buffered `Result`.

    Parameters:

      - object –

        The statement to be executed. This is always an object that is in both the `ClauseElement` and `Executable` hierarchies, including:

        - `Select`

        - `Insert`, `Update`, `Delete`

        - `TextClause` and `TextualSelect`

        - `DDL` and objects which inherit from `ExecutableDDLElement`

      - parameters – parameters which will be bound into the statement. This may be either a dictionary of parameter names to values, or a mutable sequence (e.g. a list) of dictionaries. When a list of dictionaries is passed, the underlying statement execution will make use of the DBAPI `cursor.executemany()` method. When a single dictionary is passed, the DBAPI `cursor.execute()` method will be used.

      - execution_options – optional dictionary of execution options, which will be associated with the statement execution. This dictionary can provide a subset of the options that are accepted by `Connection.execution_options()`.

    Returns:

      a `Result` object.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async execution_options(**opt: Any) → AsyncConnection

    Set non-SQL options for the connection which take effect during execution.

    This returns this `AsyncConnection` object with the new options added.

    See `Connection.execution_options()` for full details on this method.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` get_nested_transaction() → AsyncTransaction | None

    Return an `AsyncTransaction` representing the current nested (savepoint) transaction, if any.

    This makes use of the underlying synchronous connection’s `Connection.get_nested_transaction()` method to get the current `Transaction`, which is then proxied in a new `AsyncTransaction` object.

    Added in version 1.4.0b2.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async get_raw_connection() → PoolProxiedConnection

    Return the pooled DBAPI-level connection in use by this `AsyncConnection`.

    This is a SQLAlchemy connection-pool proxied connection which then has the attribute `_ConnectionFairy.driver_connection` that refers to the actual driver connection. Its `_ConnectionFairy.dbapi_connection` refers instead to an `AdaptedConnection` instance that adapts the driver connection to the DBAPI protocol.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` get_transaction() → AsyncTransaction | None

    Return an `AsyncTransaction` representing the current transaction, if any.

    This makes use of the underlying synchronous connection’s `Connection.get_transaction()` method to get the current `Transaction`, which is then proxied in a new `AsyncTransaction` object.

    Added in version 1.4.0b2.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` in_nested_transaction() → bool

    Return True if a transaction is in progress.

    Added in version 1.4.0b2.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` in_transaction() → bool

    Return True if a transaction is in progress.

  attribute `sqlalchemy.ext.asyncio.AsyncConnection.` info

    Return the `Connection.info` dictionary of the underlying `Connection`.

    This dictionary is freely writable for user-defined state to be associated with the database connection.

    This attribute is only available if the `AsyncConnection` is currently connected. If the `AsyncConnection.closed` attribute is `True`, then accessing this attribute will raise `ResourceClosedError`.

    Added in version 1.4.0b2.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async invalidate(exception: BaseException | None = None) → None

    Invalidate the underlying DBAPI connection associated with this `Connection`.

    See the method `Connection.invalidate()` for full detail on this method.

  property invalidated: Any

    Return True if this connection was invalidated.

    Proxied for the `Connection` class on behalf of the `AsyncConnection` class.

    This does not indicate whether or not the connection was invalidated at the pool level, however

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async rollback() → None

    Roll back the transaction that is currently in progress.

    This method rolls back the current transaction if one has been started. If no transaction was started, the method has no effect. If a transaction was started and the connection is in an invalidated state, the transaction is cleared using this method.

    A transaction is begun on a `Connection` automatically whenever a statement is first executed, or when the `Connection.begin()` method is called.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async run_sync(fn: ~typing.Callable[[~typing.Concatenate[~sqlalchemy.engine.base.Connection, ~_P]], ~sqlalchemy.ext.asyncio.engine._T], *arg: ~typing.~_P, **kw: ~typing.~_P) → _T

    Invoke the given synchronous (i.e. not async) callable, passing a synchronous-style `Connection` as the first argument.

    This method allows traditional synchronous SQLAlchemy functions to run within the context of an asyncio application.

    E.g.:

        def do_something_with_core(conn: Connection, arg1: int, arg2: str) -> str:
            """A synchronous function that does not require awaiting

            :param conn: a Core SQLAlchemy Connection, used synchronously

            :return: an optional return value is supported

            """
            conn.execute(some_table.insert().values(int_col=arg1, str_col=arg2))
            return "success"

        async def do_something_async(async_engine: AsyncEngine) -> None:
            """an async function that uses awaiting"""

            async with async_engine.begin() as async_conn:
                # run do_something_with_core() with a sync-style
                # Connection, proxied into an awaitable
                return_code = await async_conn.run_sync(
                    do_something_with_core, 5, "strval"
                )
                print(return_code)

    This method maintains the asyncio event loop all the way through to the database connection by running the given callable in a specially instrumented greenlet.

    The most rudimentary use of `AsyncConnection.run_sync()` is to invoke methods such as `MetaData.create_all()`, given an `AsyncConnection` that needs to be provided to `MetaData.create_all()` as a `Connection` object:

        # run metadata.create_all(conn) with a sync-style Connection,
        # proxied into an awaitable
        with async_engine.begin() as conn:
            await conn.run_sync(metadata.create_all)

    Note

    The provided callable is invoked inline within the asyncio event loop, and will block on traditional IO calls. IO within this callable should only call into SQLAlchemy’s asyncio database APIs which will be properly adapted to the greenlet context.

    See also

    `AsyncSession.run_sync()`

    Running Synchronous Methods and Functions under asyncio

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async scalar(statement: Executable, parameters: _CoreSingleExecuteParams | None = None, *, execution_options: CoreExecuteOptionsParameter | None = None) → Any

    Executes a SQL statement construct and returns a scalar object.

    This method is shorthand for invoking the `Result.scalar()` method after invoking the `Connection.execute()` method. Parameters are equivalent.

    Returns:

      a scalar Python value representing the first column of the first row returned.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async scalars(statement: Executable, parameters: _CoreAnyExecuteParams | None = None, *, execution_options: CoreExecuteOptionsParameter | None = None) → ScalarResult[Any]

    Executes a SQL statement construct and returns a scalar objects.

    This method is shorthand for invoking the `Result.scalars()` method after invoking the `Connection.execute()` method. Parameters are equivalent.

    Returns:

      a `ScalarResult` object.

    Added in version 1.4.24.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` async start(is_ctxmanager: bool = False) → AsyncConnection

    Start this `AsyncConnection` object’s context outside of using a Python `with:` block.

  method `sqlalchemy.ext.asyncio.AsyncConnection.` stream(statement: Executable, parameters: _CoreAnyExecuteParams | None = None, *, execution_options: CoreExecuteOptionsParameter | None = None) → AsyncIterator[AsyncResult[Any]]

    Execute a statement and return an awaitable yielding a `AsyncResult` object.

    E.g.:

        result = await conn.stream(stmt)
        async for row in result:
            print(f"{row}")

    The `AsyncConnection.stream()` method supports optional context manager use against the `AsyncResult` object, as in:

        async with conn.stream(stmt) as result:
            async for row in result:
                print(f"{row}")

    In the above pattern, the `AsyncResult.close()` method is invoked unconditionally, even if the iterator is interrupted by an exception throw. Context manager use remains optional, however, and the function may be called in either an `async with fn():` or `await fn()` style.

    Added in version 2.0.0b3: added context manager support

    Returns:

      an awaitable object that will yield an `AsyncResult` object.

    See also

    `AsyncConnection.stream_scalars()`

  method `sqlalchemy.ext.asyncio.AsyncConnection.` stream_scalars(statement: Executable, parameters: _CoreSingleExecuteParams | None = None, *, execution_options: CoreExecuteOptionsParameter | None = None) → AsyncIterator[AsyncScalarResult[Any]]

    Execute a statement and return an awaitable yielding a `AsyncScalarResult` object.

    E.g.:

        result = await conn.stream_scalars(stmt)
        async for scalar in result:
            print(f"{scalar}")

    This method is shorthand for invoking the `AsyncResult.scalars()` method after invoking the `Connection.stream()` method. Parameters are equivalent.

    The `AsyncConnection.stream_scalars()` method supports optional context manager use against the `AsyncScalarResult` object, as in:

        async with conn.stream_scalars(stmt) as result:
            async for scalar in result:
                print(f"{scalar}")

    In the above pattern, the `AsyncScalarResult.close()` method is invoked unconditionally, even if the iterator is interrupted by an exception throw. Context manager use remains optional, however, and the function may be called in either an `async with fn():` or `await fn()` style.

    Added in version 2.0.0b3: added context manager support

    Returns:

      an awaitable object that will yield an `AsyncScalarResult` object.

    Added in version 1.4.24.

    See also

    `AsyncConnection.stream()`

  attribute `sqlalchemy.ext.asyncio.AsyncConnection.` sync_connection: Connection | None

    Reference to the sync-style `Connection` this `AsyncConnection` proxies requests towards.

    This instance can be used as an event target.

    See also

    Using events with the asyncio extension

  attribute `sqlalchemy.ext.asyncio.AsyncConnection.` sync_engine: Engine

    Reference to the sync-style `Engine` this `AsyncConnection` is associated with via its underlying `Connection`.

    This instance can be used as an event target.

    See also

    Using events with the asyncio extension

class sqlalchemy.ext.asyncio.AsyncTransaction

  inherits from `sqlalchemy.ext.asyncio.base.ProxyComparable`, `sqlalchemy.ext.asyncio.base.StartableContext`

  An asyncio proxy for a `Transaction`.

  Member Name | Description
  --- | ---
  close() | Close this `AsyncTransaction`.
  commit() | Commit this `AsyncTransaction`.
  rollback() | Roll back this `AsyncTransaction`.
  start() | Start this `AsyncTransaction` object’s context outside of using a Python `with:` block.

  method `sqlalchemy.ext.asyncio.AsyncTransaction.` async close() → None

    Close this `AsyncTransaction`.

    If this transaction is the base transaction in a begin/commit nesting, the transaction will rollback(). Otherwise, the method returns.

    This is used to cancel a Transaction without affecting the scope of an enclosing transaction.

  method `sqlalchemy.ext.asyncio.AsyncTransaction.` async commit() → None

    Commit this `AsyncTransaction`.

  method `sqlalchemy.ext.asyncio.AsyncTransaction.` async rollback() → None

    Roll back this `AsyncTransaction`.

  method `sqlalchemy.ext.asyncio.AsyncTransaction.` async start(is_ctxmanager: bool = False) → AsyncTransaction

    Start this `AsyncTransaction` object’s context outside of using a Python `with:` block.

## Result Set API Documentation

The `AsyncResult` object is an async-adapted version of the `Result` object. It is only returned when using the `AsyncConnection.stream()` or `AsyncSession.stream()` methods, which return a result object that is on top of an active database cursor.

Object Name | Description
--- | ---
AsyncMappingResult | A wrapper for a `AsyncResult` that returns dictionary values rather than `Row` values.
AsyncResult | An asyncio wrapper around a `Result` object.
AsyncScalarResult | A wrapper for a `AsyncResult` that returns scalar values rather than `Row` values.
AsyncTupleResult | A `AsyncResult` that’s typed as returning plain Python tuples instead of rows.

class sqlalchemy.ext.asyncio.AsyncResult

  inherits from `sqlalchemy.engine._WithKeys`, `sqlalchemy.ext.asyncio.AsyncCommon`

  An asyncio wrapper around a `Result` object.

  The `AsyncResult` only applies to statement executions that use a server-side cursor. It is returned only from the `AsyncConnection.stream()` and `AsyncSession.stream()` methods.

  Note

  As is the case with `Result`, this object is used for ORM results returned by `AsyncSession.execute()`, which can yield instances of ORM mapped objects either individually or within tuple-like rows. Note that these result objects do not deduplicate instances or rows automatically as is the case with the legacy `Query` object. For in-Python de-duplication of instances or rows, use the `AsyncResult.unique()` modifier method.

  Added in version 1.4.

  Member Name | Description
  --- | ---
  all() | Return all rows in a list.
  close() | Close this result.
  columns() | Establish the columns that should be returned in each row.
  fetchall() | A synonym for the `AsyncResult.all()` method.
  fetchmany() | Fetch many rows.
  fetchone() | Fetch one row.
  first() | Fetch the first row or `None` if no row is present.
  freeze() | Return a callable object that will produce copies of this `AsyncResult` when invoked.
  keys() | Return an iterable view which yields the string keys that would be represented by each `Row`.
  mappings() | Apply a mappings filter to returned rows, returning an instance of `AsyncMappingResult`.
  one() | Return exactly one row or raise an exception.
  one_or_none() | Return at most one result or raise an exception.
  partitions() | Iterate through sub-lists of rows of the size given.
  scalar() | Fetch the first column of the first row, and close the result set.
  scalar_one() | Return exactly one scalar result or raise an exception.
  scalar_one_or_none() | Return exactly one scalar result or `None`.
  scalars() | Return an `AsyncScalarResult` filtering object which will return single elements rather than `Row` objects.
  tuples() | Apply a “typed tuple” typing filter to returned rows.
  unique() | Apply unique filtering to the objects returned by this `AsyncResult`.
  yield_per() | Configure the row-fetching strategy to fetch `num` rows at a time.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async all() → Sequence[Row[_TP]]

    Return all rows in a list.

    Closes the result set after invocation. Subsequent invocations will return an empty list.

    Returns:

      a list of `Row` objects.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async close() → None

    inherited from the `AsyncCommon.close()` method of `AsyncCommon`

    Close this result.

  property closed: bool

    proxies the .closed attribute of the underlying result object, if any, else raises `AttributeError`.

    Added in version 2.0.0b3.

  method `sqlalchemy.ext.asyncio.AsyncResult.` columns(*col_expressions: _KeyIndexType) → Self

    Establish the columns that should be returned in each row.

    Refer to `Result.columns()` in the synchronous SQLAlchemy API for a complete behavioral description.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async fetchall() → Sequence[Row[_TP]]

    A synonym for the `AsyncResult.all()` method.

    Added in version 2.0.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async fetchmany(size: int | None = None) → Sequence[Row[_TP]]

    Fetch many rows.

    When all rows are exhausted, returns an empty list.

    This method is provided for backwards compatibility with SQLAlchemy 1.x.x.

    To fetch rows in groups, use the `AsyncResult.partitions()` method.

    Returns:

      a list of `Row` objects.

    See also

    `AsyncResult.partitions()`

  method `sqlalchemy.ext.asyncio.AsyncResult.` async fetchone() → Row[_TP] | None

    Fetch one row.

    When all rows are exhausted, returns None.

    This method is provided for backwards compatibility with SQLAlchemy 1.x.x.

    To fetch the first row of a result only, use the `AsyncResult.first()` method. To iterate through all rows, iterate the `AsyncResult` object directly.

    Returns:

      a `Row` object if no filters are applied, or `None` if no rows remain.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async first() → Row[_TP] | None

    Fetch the first row or `None` if no row is present.

    Closes the result set and discards remaining rows.

    Note

    This method returns one row, e.g. tuple, by default. To return exactly one single scalar value, that is, the first column of the first row, use the `AsyncResult.scalar()` method, or combine `AsyncResult.scalars()` and `AsyncResult.first()`.

    Additionally, in contrast to the behavior of the legacy ORM `Query.first()` method, no limit is applied to the SQL query which was invoked to produce this `AsyncResult`; for a DBAPI driver that buffers results in memory before yielding rows, all rows will be sent to the Python process and all but the first row will be discarded.

    See also

    ORM Query Unified with Core Select

    Returns:

      a `Row` object, or None if no rows remain.

    See also

    `AsyncResult.scalar()`

    `AsyncResult.one()`

  method `sqlalchemy.ext.asyncio.AsyncResult.` async freeze() → FrozenResult[_TP]

    Return a callable object that will produce copies of this `AsyncResult` when invoked.

    The callable object returned is an instance of `FrozenResult`.

    This is used for result set caching. The method must be called on the result when it has been unconsumed, and calling the method will consume the result fully. When the `FrozenResult` is retrieved from a cache, it can be called any number of times where it will produce a new `Result` object each time against its stored set of rows.

    See also

    Re-Executing Statements - example usage within the ORM to implement a result-set cache.

  method `sqlalchemy.ext.asyncio.AsyncResult.` keys() → RMKeyView

    inherited from the `sqlalchemy.engine._WithKeys.keys` method of `sqlalchemy.engine._WithKeys`

    Return an iterable view which yields the string keys that would be represented by each `Row`.

    The keys can represent the labels of the columns returned by a core statement or the names of the orm classes returned by an orm execution.

    The view also can be tested for key containment using the Python `in` operator, which will test both for the string keys represented in the view, as well as for alternate keys such as column objects.

    Changed in version 1.4: a key view object is returned rather than a plain list.

  method `sqlalchemy.ext.asyncio.AsyncResult.` mappings() → AsyncMappingResult

    Apply a mappings filter to returned rows, returning an instance of `AsyncMappingResult`.

    When this filter is applied, fetching rows will return `RowMapping` objects instead of `Row` objects.

    Returns:

      a new `AsyncMappingResult` filtering object referring to the underlying `Result` object.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async one() → Row[_TP]

    Return exactly one row or raise an exception.

    Raises `NoResultFound` if the result returns no rows, or `MultipleResultsFound` if multiple rows would be returned.

    Note

    This method returns one row, e.g. tuple, by default. To return exactly one single scalar value, that is, the first column of the first row, use the `AsyncResult.scalar_one()` method, or combine `AsyncResult.scalars()` and `AsyncResult.one()`.

    Added in version 1.4.

    Returns:

      The first `Row`.

    Raises:

      `MultipleResultsFound`, `NoResultFound`

    See also

    `AsyncResult.first()`

    `AsyncResult.one_or_none()`

    `AsyncResult.scalar_one()`

  method `sqlalchemy.ext.asyncio.AsyncResult.` async one_or_none() → Row[_TP] | None

    Return at most one result or raise an exception.

    Returns `None` if the result has no rows. Raises `MultipleResultsFound` if multiple rows are returned.

    Added in version 1.4.

    Returns:

      The first `Row` or `None` if no row is available.

    Raises:

      `MultipleResultsFound`

    See also

    `AsyncResult.first()`

    `AsyncResult.one()`

  method `sqlalchemy.ext.asyncio.AsyncResult.` async partitions(size: int | None = None) → AsyncIterator[Sequence[Row[_TP]]]

    Iterate through sub-lists of rows of the size given.

    An async iterator is returned:

        async def scroll_results(connection):
            result = await connection.stream(select(users_table))

            async for partition in result.partitions(100):
                print("list of rows: %s" % partition)

    Refer to `Result.partitions()` in the synchronous SQLAlchemy API for a complete behavioral description.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async scalar() → Any

    Fetch the first column of the first row, and close the result set.

    Returns `None` if there are no rows to fetch.

    No validation is performed to test if additional rows remain.

    After calling this method, the object is fully closed, e.g. the `CursorResult.close()` method will have been called.

    Returns:

      a Python scalar value, or `None` if no rows remain.

  method `sqlalchemy.ext.asyncio.AsyncResult.` async scalar_one() → Any

    Return exactly one scalar result or raise an exception.

    This is equivalent to calling `AsyncResult.scalars()` and then `AsyncScalarResult.one()`.

    See also

    `AsyncScalarResult.one()`

    `AsyncResult.scalars()`

  method `sqlalchemy.ext.asyncio.AsyncResult.` async scalar_one_or_none() → Any | None

    Return exactly one scalar result or `None`.

    This is equivalent to calling `AsyncResult.scalars()` and then `AsyncScalarResult.one_or_none()`.

    See also

    `AsyncScalarResult.one_or_none()`

    `AsyncResult.scalars()`

  method `sqlalchemy.ext.asyncio.AsyncResult.` scalars(index: _KeyIndexType = 0) → AsyncScalarResult[Any]

    Return an `AsyncScalarResult` filtering object which will return single elements rather than `Row` objects.

    Refer to `Result.scalars()` in the synchronous SQLAlchemy API for a complete behavioral description.

    Parameters:

      index – integer or row key indicating the column to be fetched from each row, defaults to `0` indicating the first column.

    Returns:

      a new `AsyncScalarResult` filtering object referring to this `AsyncResult` object.

  property t: AsyncTupleResult[_TP]

    Apply a “typed tuple” typing filter to returned rows.

    The `AsyncResult.t` attribute is a synonym for calling the `AsyncResult.tuples()` method.

    Added in version 2.0.

  method `sqlalchemy.ext.asyncio.AsyncResult.` tuples() → AsyncTupleResult[_TP]

    Apply a “typed tuple” typing filter to returned rows.

    This method returns the same `AsyncResult` object at runtime, however annotates as returning a `AsyncTupleResult` object that will indicate to PEP 484 typing tools that plain typed `Tuple` instances are returned rather than rows. This allows tuple unpacking and `__getitem__` access of `Row` objects to by typed, for those cases where the statement invoked itself included typing information.

    Added in version 2.0.

    Returns:

      the `AsyncTupleResult` type at typing time.

    See also

    `AsyncResult.t` - shorter synonym

    `Row.t` - `Row` version

  method `sqlalchemy.ext.asyncio.AsyncResult.` unique(strategy: _UniqueFilterType | None = None) → Self

    Apply unique filtering to the objects returned by this `AsyncResult`.

    Refer to `Result.unique()` in the synchronous SQLAlchemy API for a complete behavioral description.

  method `sqlalchemy.ext.asyncio.AsyncResult.` yield_per(num: int) → Self

    inherited from the `FilterResult.yield_per()` method of `FilterResult`

    Configure the row-fetching strategy to fetch `num` rows at a time.

    The `FilterResult.yield_per()` method is a pass through to the `Result.yield_per()` method. See that method’s documentation for usage notes.

    Added in version 1.4.40: - added `FilterResult.yield_per()` so that the method is available on all result set implementations

    See also

    Using Server Side Cursors (a.k.a. stream results) - describes Core behavior for `Result.yield_per()`

    Fetching Large Result Sets with Yield Per - in the ORM Querying Guide

class sqlalchemy.ext.asyncio.AsyncScalarResult

  inherits from `sqlalchemy.ext.asyncio.AsyncCommon`

  A wrapper for a `AsyncResult` that returns scalar values rather than `Row` values.

  The `AsyncScalarResult` object is acquired by calling the `AsyncResult.scalars()` method.

  Refer to the `ScalarResult` object in the synchronous SQLAlchemy API for a complete behavioral description.

  Added in version 1.4.

  Member Name | Description
  --- | ---
  all() | Return all scalar values in a list.
  close() | Close this result.
  fetchall() | A synonym for the `AsyncScalarResult.all()` method.
  fetchmany() | Fetch many objects.
  first() | Fetch the first object or `None` if no object is present.
  one() | Return exactly one object or raise an exception.
  one_or_none() | Return at most one object or raise an exception.
  partitions() | Iterate through sub-lists of elements of the size given.
  unique() | Apply unique filtering to the objects returned by this `AsyncScalarResult`.
  yield_per() | Configure the row-fetching strategy to fetch `num` rows at a time.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async all() → Sequence[_R]

    Return all scalar values in a list.

    Equivalent to `AsyncResult.all()` except that scalar values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async close() → None

    inherited from the `AsyncCommon.close()` method of `AsyncCommon`

    Close this result.

  property closed: bool

    proxies the .closed attribute of the underlying result object, if any, else raises `AttributeError`.

    Added in version 2.0.0b3.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async fetchall() → Sequence[_R]

    A synonym for the `AsyncScalarResult.all()` method.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async fetchmany(size: int | None = None) → Sequence[_R]

    Fetch many objects.

    Equivalent to `AsyncResult.fetchmany()` except that scalar values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async first() → _R | None

    Fetch the first object or `None` if no object is present.

    Equivalent to `AsyncResult.first()` except that scalar values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async one() → _R

    Return exactly one object or raise an exception.

    Equivalent to `AsyncResult.one()` except that scalar values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async one_or_none() → _R | None

    Return at most one object or raise an exception.

    Equivalent to `AsyncResult.one_or_none()` except that scalar values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` async partitions(size: int | None = None) → AsyncIterator[Sequence[_R]]

    Iterate through sub-lists of elements of the size given.

    Equivalent to `AsyncResult.partitions()` except that scalar values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` unique(strategy: _UniqueFilterType | None = None) → Self

    Apply unique filtering to the objects returned by this `AsyncScalarResult`.

    See `AsyncResult.unique()` for usage details.

  method `sqlalchemy.ext.asyncio.AsyncScalarResult.` yield_per(num: int) → Self

    inherited from the `FilterResult.yield_per()` method of `FilterResult`

    Configure the row-fetching strategy to fetch `num` rows at a time.

    The `FilterResult.yield_per()` method is a pass through to the `Result.yield_per()` method. See that method’s documentation for usage notes.

    Added in version 1.4.40: - added `FilterResult.yield_per()` so that the method is available on all result set implementations

    See also

    Using Server Side Cursors (a.k.a. stream results) - describes Core behavior for `Result.yield_per()`

    Fetching Large Result Sets with Yield Per - in the ORM Querying Guide

class sqlalchemy.ext.asyncio.AsyncMappingResult

  inherits from `sqlalchemy.engine._WithKeys`, `sqlalchemy.ext.asyncio.AsyncCommon`

  A wrapper for a `AsyncResult` that returns dictionary values rather than `Row` values.

  The `AsyncMappingResult` object is acquired by calling the `AsyncResult.mappings()` method.

  Refer to the `MappingResult` object in the synchronous SQLAlchemy API for a complete behavioral description.

  Added in version 1.4.

  Member Name | Description
  --- | ---
  all() | Return all rows in a list.
  close() | Close this result.
  columns() | Establish the columns that should be returned in each row.
  fetchall() | A synonym for the `AsyncMappingResult.all()` method.
  fetchmany() | Fetch many rows.
  fetchone() | Fetch one object.
  first() | Fetch the first object or `None` if no object is present.
  keys() | Return an iterable view which yields the string keys that would be represented by each `Row`.
  one() | Return exactly one object or raise an exception.
  one_or_none() | Return at most one object or raise an exception.
  partitions() | Iterate through sub-lists of elements of the size given.
  unique() | Apply unique filtering to the objects returned by this `AsyncMappingResult`.
  yield_per() | Configure the row-fetching strategy to fetch `num` rows at a time.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async all() → Sequence[RowMapping]

    Return all rows in a list.

    Equivalent to `AsyncResult.all()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async close() → None

    inherited from the `AsyncCommon.close()` method of `AsyncCommon`

    Close this result.

  property closed: bool

    proxies the .closed attribute of the underlying result object, if any, else raises `AttributeError`.

    Added in version 2.0.0b3.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` columns(*col_expressions: _KeyIndexType) → Self

    Establish the columns that should be returned in each row.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async fetchall() → Sequence[RowMapping]

    A synonym for the `AsyncMappingResult.all()` method.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async fetchmany(size: int | None = None) → Sequence[RowMapping]

    Fetch many rows.

    Equivalent to `AsyncResult.fetchmany()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async fetchone() → RowMapping | None

    Fetch one object.

    Equivalent to `AsyncResult.fetchone()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async first() → RowMapping | None

    Fetch the first object or `None` if no object is present.

    Equivalent to `AsyncResult.first()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` keys() → RMKeyView

    inherited from the `sqlalchemy.engine._WithKeys.keys` method of `sqlalchemy.engine._WithKeys`

    Return an iterable view which yields the string keys that would be represented by each `Row`.

    The keys can represent the labels of the columns returned by a core statement or the names of the orm classes returned by an orm execution.

    The view also can be tested for key containment using the Python `in` operator, which will test both for the string keys represented in the view, as well as for alternate keys such as column objects.

    Changed in version 1.4: a key view object is returned rather than a plain list.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async one() → RowMapping

    Return exactly one object or raise an exception.

    Equivalent to `AsyncResult.one()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async one_or_none() → RowMapping | None

    Return at most one object or raise an exception.

    Equivalent to `AsyncResult.one_or_none()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` async partitions(size: int | None = None) → AsyncIterator[Sequence[RowMapping]]

    Iterate through sub-lists of elements of the size given.

    Equivalent to `AsyncResult.partitions()` except that `RowMapping` values, rather than `Row` objects, are returned.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` unique(strategy: _UniqueFilterType | None = None) → Self

    Apply unique filtering to the objects returned by this `AsyncMappingResult`.

    See `AsyncResult.unique()` for usage details.

  method `sqlalchemy.ext.asyncio.AsyncMappingResult.` yield_per(num: int) → Self

    inherited from the `FilterResult.yield_per()` method of `FilterResult`

    Configure the row-fetching strategy to fetch `num` rows at a time.

    The `FilterResult.yield_per()` method is a pass through to the `Result.yield_per()` method. See that method’s documentation for usage notes.

    Added in version 1.4.40: - added `FilterResult.yield_per()` so that the method is available on all result set implementations

    See also

    Using Server Side Cursors (a.k.a. stream results) - describes Core behavior for `Result.yield_per()`

    Fetching Large Result Sets with Yield Per - in the ORM Querying Guide

class sqlalchemy.ext.asyncio.AsyncTupleResult

  inherits from `sqlalchemy.ext.asyncio.AsyncCommon`, `sqlalchemy.util.langhelpers.TypingOnly`

  A `AsyncResult` that’s typed as returning plain Python tuples instead of rows.

  Since `Row` acts like a tuple in every way already, this class is a typing only class, regular `AsyncResult` is still used at runtime.

## ORM Session API Documentation

Object Name | Description
--- | ---
async_object_session(instance) | Return the `AsyncSession` to which the given instance belongs.
async_scoped_session | Provides scoped management of `AsyncSession` objects.
async_session(session) | Return the `AsyncSession` which is proxying the given `Session` object, if any.
async_sessionmaker | A configurable `AsyncSession` factory.
AsyncAttrs | Mixin class which provides an awaitable accessor for all attributes.
AsyncSession | Asyncio version of `Session`.
AsyncSessionTransaction | A wrapper for the ORM `SessionTransaction` object.
close_all_sessions() | Close all `AsyncSession` sessions.

function sqlalchemy.ext.asyncio.async_object_session(instance: object) → AsyncSession | None

  Return the `AsyncSession` to which the given instance belongs.

  This function makes use of the sync-API function `object_session` to retrieve the `Session` which refers to the given instance, and from there links it to the original `AsyncSession`.

  If the `AsyncSession` has been garbage collected, the return value is `None`.

  This functionality is also available from the `InstanceState.async_session` accessor.

  Parameters:

    instance – an ORM mapped instance

  Returns:

    an `AsyncSession` object, or `None`.

  Added in version 1.4.18.

function sqlalchemy.ext.asyncio.async_session(session: Session) → AsyncSession | None

  Return the `AsyncSession` which is proxying the given `Session` object, if any.

  Parameters:

    session – a `Session` instance.

  Returns:

    a `AsyncSession` instance, or `None`.

  Added in version 1.4.18.

function async sqlalchemy.ext.asyncio.close_all_sessions() → None

  Close all `AsyncSession` sessions.

  Added in version 2.0.23.

  See also

  `close_all_sessions()`

class sqlalchemy.ext.asyncio.async_sessionmaker

  inherits from `typing.Generic`

  A configurable `AsyncSession` factory.

  The `async_sessionmaker` factory works in the same way as the `sessionmaker` factory, to generate new `AsyncSession` objects when called, creating them given the configurational arguments established here.

  e.g.:

      from sqlalchemy.ext.asyncio import create_async_engine
      from sqlalchemy.ext.asyncio import AsyncSession
      from sqlalchemy.ext.asyncio import async_sessionmaker

      async def run_some_sql(
          async_session: async_sessionmaker[AsyncSession],
      ) -> None:
          async with async_session() as session:
              session.add(SomeObject(data="object"))
              session.add(SomeOtherObject(name="other object"))
              await session.commit()

      async def main() -> None:
          # an AsyncEngine, which the AsyncSession will use for connection
          # resources
          engine = create_async_engine(
              "postgresql+asyncpg://scott:tiger@localhost/"
          )

          # create a reusable factory for new AsyncSession instances
          async_session = async_sessionmaker(engine)

          await run_some_sql(async_session)

          await engine.dispose()

  The `async_sessionmaker` is useful so that different parts of a program can create new `AsyncSession` objects with a fixed configuration established up front. Note that `AsyncSession` objects may also be instantiated directly when not using `async_sessionmaker`.

  Added in version 2.0: `async_sessionmaker` provides a `sessionmaker` class that’s dedicated to the `AsyncSession` object, including pep-484 typing support.

  See also

  Synopsis - ORM - shows example use

  `sessionmaker` - general overview of the

    `sessionmaker` architecture

  Opening and Closing a Session - introductory text on creating sessions using `sessionmaker`.

  Member Name | Description
  --- | ---
  __call__() | Produce a new `AsyncSession` object using the configuration established in this `async_sessionmaker`.
  __init__() | Construct a new `async_sessionmaker`.
  begin() | Produce a context manager that both provides a new `AsyncSession` as well as a transaction that commits.
  configure() | (Re)configure the arguments for this async_sessionmaker.

  method `sqlalchemy.ext.asyncio.async_sessionmaker.` __call__(**local_kw: Any) → _AS

    Produce a new `AsyncSession` object using the configuration established in this `async_sessionmaker`.

    In Python, the `__call__` method is invoked on an object when it is “called” in the same way as a function:

        AsyncSession = async_sessionmaker(async_engine, expire_on_commit=False)
        session = AsyncSession()  # invokes sessionmaker.__call__()

  method `sqlalchemy.ext.asyncio.async_sessionmaker.` __init__(bind: _AsyncSessionBind | None = None, *, class_: Type[_AS] = <class 'sqlalchemy.ext.asyncio.session.AsyncSession'>, autoflush: bool = True, expire_on_commit: bool = True, info: _InfoType | None = None, **kw: Any)

    Construct a new `async_sessionmaker`.

    All arguments here except for `class_` correspond to arguments accepted by `Session` directly. See the `AsyncSession.__init__()` docstring for more details on parameters.

  method `sqlalchemy.ext.asyncio.async_sessionmaker.` begin() → _AsyncSessionContextManager[_AS]

    Produce a context manager that both provides a new `AsyncSession` as well as a transaction that commits.

    e.g.:

        async def main():
            Session = async_sessionmaker(some_engine)

            async with Session.begin() as session:
                session.add(some_object)

            # commits transaction, closes session

  method `sqlalchemy.ext.asyncio.async_sessionmaker.` configure(**new_kw: Any) → None

    (Re)configure the arguments for this async_sessionmaker.

    e.g.:

        AsyncSession = async_sessionmaker(some_engine)

        AsyncSession.configure(bind=create_async_engine("sqlite+aiosqlite://"))

class sqlalchemy.ext.asyncio.async_scoped_session

  inherits from `typing.Generic`

  Provides scoped management of `AsyncSession` objects.

  See the section Using asyncio scoped session for usage details.

  Added in version 1.4.19.

  Member Name | Description
  --- | ---
  __call__() | Return the current `AsyncSession`, creating it using the `scoped_session.session_factory` if not present.
  __init__() | Construct a new `async_scoped_session`.
  aclose() | A synonym for `AsyncSession.close()`.
  add() | Place an object into this `Session`.
  add_all() | Add the given collection of instances to this `Session`.
  begin() | Return an `AsyncSessionTransaction` object.
  begin_nested() | Return an `AsyncSessionTransaction` object which will begin a “nested” transaction, e.g. SAVEPOINT.
  close() | Close out the transactional resources and ORM objects used by this `AsyncSession`.
  close_all() | Close all `AsyncSession` sessions.
  commit() | Commit the current transaction in progress.
  configure() | reconfigure the `sessionmaker` used by this `scoped_session`.
  connection() | Return a `AsyncConnection` object corresponding to this `Session` object’s transactional state.
  delete() | Mark an instance as deleted.
  execute() | Execute a statement and return a buffered `Result` object.
  expire() | Expire the attributes on an instance.
  expire_all() | Expires all persistent instances within this Session.
  expunge() | Remove the instance from this `Session`.
  expunge_all() | Remove all object instances from this `Session`.
  flush() | Flush all the object changes to the database.
  get() | Return an instance based on the given primary key identifier, or `None` if not found.
  get_bind() | Return a “bind” to which the synchronous proxied `Session` is bound.
  get_one() | Return an instance based on the given primary key identifier, or raise an exception if not found.
  identity_key() | Return an identity key.
  invalidate() | Close this Session, using connection invalidation.
  is_modified() | Return `True` if the given instance has locally modified attributes.
  merge() | Copy the state of a given instance into a corresponding instance within this `AsyncSession`.
  object_session() | Return the `Session` to which an object belongs.
  refresh() | Expire and refresh the attributes on the given instance.
  remove() | Dispose of the current `AsyncSession`, if present.
  reset() | Close out the transactional resources and ORM objects used by this `Session`, resetting the session to its initial state.
  rollback() | Rollback the current transaction in progress.
  scalar() | Execute a statement and return a scalar result.
  scalars() | Execute a statement and return scalar results.
  session_factory | The session_factory provided to __init__ is stored in this attribute and may be accessed at a later time. This can be useful when a new non-scoped `AsyncSession` is needed.
  stream() | Execute a statement and return a streaming `AsyncResult` object.
  stream_scalars() | Execute a statement and return a stream of scalar results.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` __call__(**kw: Any) → _AS

    Return the current `AsyncSession`, creating it using the `scoped_session.session_factory` if not present.

    Parameters:

      **kw – Keyword arguments will be passed to the `scoped_session.session_factory` callable, if an existing `AsyncSession` is not present. If the `AsyncSession` is present and keyword arguments have been passed, `InvalidRequestError` is raised.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` __init__(session_factory: async_sessionmaker[_AS], scopefunc: Callable[[], Any])

    Construct a new `async_scoped_session`.

    Parameters:

      - session_factory – a factory to create new `AsyncSession` instances. This is usually, but not necessarily, an instance of `async_sessionmaker`.

      - scopefunc – function which defines the current scope. A function such as `asyncio.current_task` may be useful here.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async aclose() → None

    A synonym for `AsyncSession.close()`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    The `AsyncSession.aclose()` name is specifically to support the Python standard library `@contextlib.aclosing` context manager function.

    Added in version 2.0.20.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` add(instance: object, _warn: bool = True) → None

    Place an object into this `Session`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Objects that are in the transient state when passed to the `Session.add()` method will move to the pending state, until the next flush, at which point they will move to the persistent state.

    Objects that are in the detached state when passed to the `Session.add()` method will move to the persistent state directly.

    If the transaction used by the `Session` is rolled back, objects which were transient when they were passed to `Session.add()` will be moved back to the transient state, and will no longer be present within this `Session`.

    See also

    `Session.add_all()`

    Adding New or Existing Items - at Basics of Using a Session

  method `sqlalchemy.ext.asyncio.async_scoped_session.` add_all(instances: Iterable[object]) → None

    Add the given collection of instances to this `Session`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    See the documentation for `Session.add()` for a general behavioral description.

    See also

    `Session.add()`

    Adding New or Existing Items - at Basics of Using a Session

  property autoflush: Any

    Proxy for the `Session.autoflush` attribute on behalf of the `AsyncSession` class.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` begin() → AsyncSessionTransaction

    Return an `AsyncSessionTransaction` object.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    The underlying `Session` will perform the “begin” action when the `AsyncSessionTransaction` object is entered:

        async with async_session.begin():
            ...  # ORM transaction is begun

    Note that database IO will not normally occur when the session-level transaction is begun, as database transactions begin on an on-demand basis. However, the begin block is async to accommodate for a `SessionEvents.after_transaction_create()` event hook that may perform IO.

    For a general description of ORM begin, see `Session.begin()`.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` begin_nested() → AsyncSessionTransaction

    Return an `AsyncSessionTransaction` object which will begin a “nested” transaction, e.g. SAVEPOINT.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Behavior is the same as that of `AsyncSession.begin()`.

    For a general description of ORM begin nested, see `Session.begin_nested()`.

    See also

    Serializable isolation / Savepoints / Transactional DDL (asyncio version) - special workarounds required with the SQLite asyncio driver in order for SAVEPOINT to work correctly.

  property bind: Any

    Proxy for the `AsyncSession.bind` attribute on behalf of the `async_scoped_session` class.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async close() → None

    Close out the transactional resources and ORM objects used by this `AsyncSession`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.close()` - main documentation for “close”

    Closing - detail on the semantics of `AsyncSession.close()` and `AsyncSession.reset()`.

  async classmethod `sqlalchemy.ext.asyncio.async_scoped_session.` close_all() → None

    Close all `AsyncSession` sessions.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Deprecated since version 2.0: The `AsyncSession.close_all()` method is deprecated and will be removed in a future release. Please refer to `close_all_sessions()`.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async commit() → None

    Commit the current transaction in progress.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.commit()` - main documentation for “commit”

  method `sqlalchemy.ext.asyncio.async_scoped_session.` configure(**kwargs: Any) → None

    reconfigure the `sessionmaker` used by this `scoped_session`.

    See `sessionmaker.configure()`.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async connection(bind_arguments: _BindArguments | None = None, execution_options: CoreExecuteOptionsParameter | None = None, **kw: Any) → AsyncConnection

    Return a `AsyncConnection` object corresponding to this `Session` object’s transactional state.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    This method may also be used to establish execution options for the database connection used by the current transaction.

    Added in version 1.4.24: Added **kw arguments which are passed through to the underlying `Session.connection()` method.

    See also

    `Session.connection()` - main documentation for “connection”

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async delete(instance: object) → None

    Mark an instance as deleted.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    The database delete operation occurs upon `flush()`.

    As this operation may need to cascade along unloaded relationships, it is awaitable to allow for those queries to take place.

    See also

    `Session.delete()` - main documentation for delete

  property deleted: Any

    The set of all instances marked as ‘deleted’ within this `Session`

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

  property dirty: Any

    The set of all persistent instances considered dirty.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    E.g.:

        some_mapped_object in session.dirty

    Instances are considered dirty when they were modified but not deleted.

    Note that this ‘dirty’ calculation is ‘optimistic’; most attribute-setting or collection modification operations will mark an instance as ‘dirty’ and place it in this set, even if there is no net change to the attribute’s value. At flush time, the value of each attribute is compared to its previously saved value, and if there’s no net change, no SQL operation will occur (this is a more expensive operation so it’s only done at flush time).

    To check if an instance has actionable net changes to its attributes, use the `Session.is_modified()` method.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async execute(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → Result[Any]

    Execute a statement and return a buffered `Result` object.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.execute()` - main documentation for execute

  method `sqlalchemy.ext.asyncio.async_scoped_session.` expire(instance: object, attribute_names: Iterable[str] | None = None) → None

    Expire the attributes on an instance.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Marks the attributes of an instance as out of date. When an expired attribute is next accessed, a query will be issued to the `Session` object’s current transactional context in order to load all expired attributes for the given instance. Note that a highly isolated transaction will return the same values as were previously read in that same transaction, regardless of changes in database state outside of that transaction.

    To expire all objects in the `Session` simultaneously, use `Session.expire_all()`.

    The `Session` object’s default behavior is to expire all state whenever the `Session.rollback()` or `Session.commit()` methods are called, so that new state can be loaded for the new transaction. For this reason, calling `Session.expire()` only makes sense for the specific case that a non-ORM SQL statement was emitted in the current transaction.

    Parameters:

      - instance – The instance to be refreshed.

      - attribute_names – optional list of string attribute names indicating a subset of attributes to be expired.

    See also

    Refreshing / Expiring - introductory material

    `Session.expire()`

    `Session.refresh()`

    `Query.populate_existing()`

  method `sqlalchemy.ext.asyncio.async_scoped_session.` expire_all() → None

    Expires all persistent instances within this Session.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    When any attributes on a persistent instance is next accessed, a query will be issued using the `Session` object’s current transactional context in order to load all expired attributes for the given instance. Note that a highly isolated transaction will return the same values as were previously read in that same transaction, regardless of changes in database state outside of that transaction.

    To expire individual objects and individual attributes on those objects, use `Session.expire()`.

    The `Session` object’s default behavior is to expire all state whenever the `Session.rollback()` or `Session.commit()` methods are called, so that new state can be loaded for the new transaction. For this reason, calling `Session.expire_all()` is not usually needed, assuming the transaction is isolated.

    See also

    Refreshing / Expiring - introductory material

    `Session.expire()`

    `Session.refresh()`

    `Query.populate_existing()`

  method `sqlalchemy.ext.asyncio.async_scoped_session.` expunge(instance: object) → None

    Remove the instance from this `Session`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This will free all internal references to the instance. Cascading will be applied according to the expunge cascade rule.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` expunge_all() → None

    Remove all object instances from this `Session`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This is equivalent to calling `expunge(obj)` on all objects in this `Session`.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async flush(objects: Sequence[Any] | None = None) → None

    Flush all the object changes to the database.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.flush()` - main documentation for flush

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async get(entity: _EntityBindKey[_O], ident: _PKIdentityArgument, *, options: Sequence[ORMOption] | None = None, populate_existing: bool = False, with_for_update: ForUpdateParameter = None, identity_token: Any | None = None, execution_options: OrmExecuteOptionsParameter = {}) → _O | None

    Return an instance based on the given primary key identifier, or `None` if not found.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.get()` - main documentation for get

  method `sqlalchemy.ext.asyncio.async_scoped_session.` get_bind(mapper: _EntityBindKey[_O] | None = None, clause: ClauseElement | None = None, bind: _SessionBind | None = None, **kw: Any) → Engine | Connection

    Return a “bind” to which the synchronous proxied `Session` is bound.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Unlike the `Session.get_bind()` method, this method is currently not used by this `AsyncSession` in any way in order to resolve engines for requests.

    Note

    This method proxies directly to the `Session.get_bind()` method, however is currently not useful as an override target, in contrast to that of the `Session.get_bind()` method. The example below illustrates how to implement custom `Session.get_bind()` schemes that work with `AsyncSession` and `AsyncEngine`.

    The pattern introduced at Custom Vertical Partitioning illustrates how to apply a custom bind-lookup scheme to a `Session` given a set of `Engine` objects. To apply a corresponding `Session.get_bind()` implementation for use with a `AsyncSession` and `AsyncEngine` objects, continue to subclass `Session` and apply it to `AsyncSession` using `AsyncSession.sync_session_class`. The inner method must continue to return `Engine` instances, which can be acquired from a `AsyncEngine` using the `AsyncEngine.sync_engine` attribute:

        # using example from "Custom Vertical Partitioning"

        import random

        from sqlalchemy.ext.asyncio import AsyncSession
        from sqlalchemy.ext.asyncio import create_async_engine
        from sqlalchemy.ext.asyncio import async_sessionmaker
        from sqlalchemy.orm import Session

        # construct async engines w/ async drivers
        engines = {
            "leader": create_async_engine("sqlite+aiosqlite:///leader.db"),
            "other": create_async_engine("sqlite+aiosqlite:///other.db"),
            "follower1": create_async_engine("sqlite+aiosqlite:///follower1.db"),
            "follower2": create_async_engine("sqlite+aiosqlite:///follower2.db"),
        }

        class RoutingSession(Session):
            def get_bind(self, mapper=None, clause=None, **kw):
                # within get_bind(), return sync engines
                if mapper and issubclass(mapper.class_, MyOtherClass):
                    return engines["other"].sync_engine
                elif self._flushing or isinstance(clause, (Update, Delete)):
                    return engines["leader"].sync_engine
                else:
                    return engines[
                        random.choice(["follower1", "follower2"])
                    ].sync_engine

        # apply to AsyncSession using sync_session_class
        AsyncSessionMaker = async_sessionmaker(sync_session_class=RoutingSession)

    The `Session.get_bind()` method is called in a non-asyncio, implicitly non-blocking context in the same manner as ORM event hooks and functions that are invoked via `AsyncSession.run_sync()`, so routines that wish to run SQL commands inside of `Session.get_bind()` can continue to do so using blocking-style code, which will be translated to implicitly async calls at the point of invoking IO on the database drivers.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async get_one(entity: _EntityBindKey[_O], ident: _PKIdentityArgument, *, options: Sequence[ORMOption] | None = None, populate_existing: bool = False, with_for_update: ForUpdateParameter = None, identity_token: Any | None = None, execution_options: OrmExecuteOptionsParameter = {}) → _O

    Return an instance based on the given primary key identifier, or raise an exception if not found.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Raises `NoResultFound` if the query selects no rows.

    ..versionadded: 2.0.22

    See also

    `Session.get_one()` - main documentation for get_one

  classmethod `sqlalchemy.ext.asyncio.async_scoped_session.` identity_key(class_: Type[Any] | None = None, ident: Any | Tuple[Any, ...] = None, *, instance: Any | None = None, row: Row[Any] | RowMapping | None = None, identity_token: Any | None = None) → _IdentityKeyType[Any]

    Return an identity key.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This is an alias of `identity_key()`.

  property identity_map: Any

    Proxy for the `Session.identity_map` attribute on behalf of the `AsyncSession` class.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

  property info: Any

    A user-modifiable dictionary.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    The initial value of this dictionary can be populated using the `info` argument to the `Session` constructor or `sessionmaker` constructor or factory methods. The dictionary here is always local to this `Session` and can be modified independently of all other `Session` objects.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async invalidate() → None

    Close this Session, using connection invalidation.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    For a complete description, see `Session.invalidate()`.

  property is_active: Any

    True if this `Session` not in “partial rollback” state.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Changed in version 1.4: The `Session` no longer begins a new transaction immediately, so this attribute will be False when the `Session` is first instantiated.

    “partial rollback” state typically indicates that the flush process of the `Session` has failed, and that the `Session.rollback()` method must be emitted in order to fully roll back the transaction.

    If this `Session` is not in a transaction at all, the `Session` will autobegin when it is first used, so in this case `Session.is_active` will return True.

    Otherwise, if this `Session` is within a transaction, and that transaction has not been rolled back internally, the `Session.is_active` will also return True.

    See also

    “This Session’s transaction has been rolled back due to a previous exception during flush.” (or similar)

    `Session.in_transaction()`

  method `sqlalchemy.ext.asyncio.async_scoped_session.` is_modified(instance: object, include_collections: bool = True) → bool

    Return `True` if the given instance has locally modified attributes.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This method retrieves the history for each instrumented attribute on the instance and performs a comparison of the current value to its previously flushed or committed value, if any.

    It is in effect a more expensive and accurate version of checking for the given instance in the `Session.dirty` collection; a full test for each attribute’s net “dirty” status is performed.

    E.g.:

        return session.is_modified(someobject)

    A few caveats to this method apply:

    - Instances present in the `Session.dirty` collection may report `False` when tested with this method. This is because the object may have received change events via attribute mutation, thus placing it in `Session.dirty`, but ultimately the state is the same as that loaded from the database, resulting in no net change here.

    - Scalar attributes may not have recorded the previously set value when a new value was applied, if the attribute was not loaded, or was expired, at the time the new value was received - in these cases, the attribute is assumed to have a change, even if there is ultimately no net change against its database value. SQLAlchemy in most cases does not need the “old” value when a set event occurs, so it skips the expense of a SQL call if the old value isn’t present, based on the assumption that an UPDATE of the scalar value is usually needed, and in those few cases where it isn’t, is less expensive on average than issuing a defensive SELECT.

      The “old” value is fetched unconditionally upon set only if the attribute container has the `active_history` flag set to `True`. This flag is set typically for primary key attributes and scalar object references that are not a simple many-to-one. To set this flag for any arbitrary mapped column, use the `active_history` argument with `column_property()`.

    Parameters:

      - instance – mapped instance to be tested for pending changes.

      - include_collections – Indicates if multivalued collections should be included in the operation. Setting this to `False` is a way to detect only local-column based properties (i.e. scalar columns or many-to-one foreign keys) that would result in an UPDATE for this instance upon flush.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async merge(instance: _O, *, load: bool = True, options: Sequence[ORMOption] | None = None) → _O

    Copy the state of a given instance into a corresponding instance within this `AsyncSession`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.merge()` - main documentation for merge

  property new: Any

    The set of all instances marked as ‘new’ within this `Session`.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

  property no_autoflush: Any

    Return a context manager that disables autoflush.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    e.g.:

        with session.no_autoflush:

            some_object = SomeClass()
            session.add(some_object)
            # won't autoflush
            some_object.related_thing = session.query(SomeRelated).first()

    Operations that proceed within the `with:` block will not be subject to flushes occurring upon query access. This is useful when initializing a series of objects which involve existing database queries, where the uncompleted object should not yet be flushed.

  classmethod `sqlalchemy.ext.asyncio.async_scoped_session.` object_session(instance: object) → Session | None

    Return the `Session` to which an object belongs.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This is an alias of `object_session()`.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async refresh(instance: object, attribute_names: Iterable[str] | None = None, with_for_update: ForUpdateParameter = None) → None

    Expire and refresh the attributes on the given instance.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    A query will be issued to the database and all attributes will be refreshed with their current database value.

    This is the async version of the `Session.refresh()` method. See that method for a complete description of all options.

    See also

    `Session.refresh()` - main documentation for refresh

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async remove() → None

    Dispose of the current `AsyncSession`, if present.

    Different from scoped_session’s remove method, this method would use await to wait for the close method of AsyncSession.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async reset() → None

    Close out the transactional resources and ORM objects used by this `Session`, resetting the session to its initial state.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Added in version 2.0.22.

    See also

    `Session.reset()` - main documentation for “reset”

    Closing - detail on the semantics of `AsyncSession.close()` and `AsyncSession.reset()`.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async rollback() → None

    Rollback the current transaction in progress.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.rollback()` - main documentation for “rollback”

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async scalar(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → Any

    Execute a statement and return a scalar result.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    See also

    `Session.scalar()` - main documentation for scalar

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async scalars(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → ScalarResult[Any]

    Execute a statement and return scalar results.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Returns:

      a `ScalarResult` object

    Added in version 1.4.24: Added `AsyncSession.scalars()`

    Added in version 1.4.26: Added `async_scoped_session.scalars()`

    See also

    `Session.scalars()` - main documentation for scalars

    `AsyncSession.stream_scalars()` - streaming version

  attribute `sqlalchemy.ext.asyncio.async_scoped_session.` session_factory: async_sessionmaker[_AS]

    The session_factory provided to __init__ is stored in this attribute and may be accessed at a later time. This can be useful when a new non-scoped `AsyncSession` is needed.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async stream(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → AsyncResult[Any]

    Execute a statement and return a streaming `AsyncResult` object.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

  method `sqlalchemy.ext.asyncio.async_scoped_session.` async stream_scalars(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → AsyncScalarResult[Any]

    Execute a statement and return a stream of scalar results.

    Proxied for the `AsyncSession` class on behalf of the `async_scoped_session` class.

    Returns:

      an `AsyncScalarResult` object

    Added in version 1.4.24.

    See also

    `Session.scalars()` - main documentation for scalars

    `AsyncSession.scalars()` - non streaming version

class sqlalchemy.ext.asyncio.AsyncAttrs

  Mixin class which provides an awaitable accessor for all attributes.

  E.g.:

      from __future__ import annotations

      from typing import List

      from sqlalchemy import ForeignKey
      from sqlalchemy import func
      from sqlalchemy.ext.asyncio import AsyncAttrs
      from sqlalchemy.orm import DeclarativeBase
      from sqlalchemy.orm import Mapped
      from sqlalchemy.orm import mapped_column
      from sqlalchemy.orm import relationship

      class Base(AsyncAttrs, DeclarativeBase):
          pass

      class A(Base):
          __tablename__ = "a"

          id: Mapped[int] = mapped_column(primary_key=True)
          data: Mapped[str]
          bs: Mapped[List[B]] = relationship()

      class B(Base):
          __tablename__ = "b"
          id: Mapped[int] = mapped_column(primary_key=True)
          a_id: Mapped[int] = mapped_column(ForeignKey("a.id"))
          data: Mapped[str]

  In the above example, the `AsyncAttrs` mixin is applied to the declarative `Base` class where it takes effect for all subclasses. This mixin adds a single new attribute `AsyncAttrs.awaitable_attrs` to all classes, which will yield the value of any attribute as an awaitable. This allows attributes which may be subject to lazy loading or deferred / unexpiry loading to be accessed such that IO can still be emitted:

      a1 = (await async_session.scalars(select(A).where(A.id == 5))).one()

      # use the lazy loader on ``a1.bs`` via the ``.awaitable_attrs``
      # interface, so that it may be awaited
      for b1 in await a1.awaitable_attrs.bs:
          print(b1)

  The `AsyncAttrs.awaitable_attrs` performs a call against the attribute that is approximately equivalent to using the `AsyncSession.run_sync()` method, e.g.:

      for b1 in await async_session.run_sync(lambda sess: a1.bs):
          print(b1)

  Added in version 2.0.13.

  See also

  Preventing Implicit IO when Using AsyncSession

  property awaitable_attrs: _AsyncAttrGetitem

    provide a namespace of all attributes on this object wrapped as awaitables.

    e.g.:

        a1 = (await async_session.scalars(select(A).where(A.id == 5))).one()

        some_attribute = await a1.awaitable_attrs.some_deferred_attribute
        some_collection = await a1.awaitable_attrs.some_collection

class sqlalchemy.ext.asyncio.AsyncSession

  inherits from `sqlalchemy.ext.asyncio.base.ReversibleProxy`

  Asyncio version of `Session`.

  The `AsyncSession` is a proxy for a traditional `Session` instance.

  The `AsyncSession` is not safe for use in concurrent tasks.. See Is the Session thread-safe? Is AsyncSession safe to share in concurrent tasks? for background.

  Added in version 1.4.

  To use an `AsyncSession` with custom `Session` implementations, see the `AsyncSession.sync_session_class` parameter.

  Member Name | Description
  --- | ---
  __init__() | Construct a new `AsyncSession`.
  aclose() | A synonym for `AsyncSession.close()`.
  add() | Place an object into this `Session`.
  add_all() | Add the given collection of instances to this `Session`.
  begin() | Return an `AsyncSessionTransaction` object.
  begin_nested() | Return an `AsyncSessionTransaction` object which will begin a “nested” transaction, e.g. SAVEPOINT.
  close() | Close out the transactional resources and ORM objects used by this `AsyncSession`.
  close_all() | Close all `AsyncSession` sessions.
  commit() | Commit the current transaction in progress.
  connection() | Return a `AsyncConnection` object corresponding to this `Session` object’s transactional state.
  delete() | Mark an instance as deleted.
  execute() | Execute a statement and return a buffered `Result` object.
  expire() | Expire the attributes on an instance.
  expire_all() | Expires all persistent instances within this Session.
  expunge() | Remove the instance from this `Session`.
  expunge_all() | Remove all object instances from this `Session`.
  flush() | Flush all the object changes to the database.
  get() | Return an instance based on the given primary key identifier, or `None` if not found.
  get_bind() | Return a “bind” to which the synchronous proxied `Session` is bound.
  get_nested_transaction() | Return the current nested transaction in progress, if any.
  get_one() | Return an instance based on the given primary key identifier, or raise an exception if not found.
  get_transaction() | Return the current root transaction in progress, if any.
  identity_key() | Return an identity key.
  in_nested_transaction() | Return True if this `Session` has begun a nested transaction, e.g. SAVEPOINT.
  in_transaction() | Return True if this `Session` has begun a transaction.
  invalidate() | Close this Session, using connection invalidation.
  is_modified() | Return `True` if the given instance has locally modified attributes.
  merge() | Copy the state of a given instance into a corresponding instance within this `AsyncSession`.
  object_session() | Return the `Session` to which an object belongs.
  refresh() | Expire and refresh the attributes on the given instance.
  reset() | Close out the transactional resources and ORM objects used by this `Session`, resetting the session to its initial state.
  rollback() | Rollback the current transaction in progress.
  run_sync() | Invoke the given synchronous (i.e. not async) callable, passing a synchronous-style `Session` as the first argument.
  scalar() | Execute a statement and return a scalar result.
  scalars() | Execute a statement and return scalar results.
  stream() | Execute a statement and return a streaming `AsyncResult` object.
  stream_scalars() | Execute a statement and return a stream of scalar results.
  sync_session | Reference to the underlying `Session` this `AsyncSession` proxies requests towards.
  sync_session_class | The class or callable that provides the underlying `Session` instance for a particular `AsyncSession`.

  method `sqlalchemy.ext.asyncio.AsyncSession.` __init__(bind: _AsyncSessionBind | None = None, *, binds: Dict[_SessionBindKey, _AsyncSessionBind] | None = None, sync_session_class: Type[Session] | None = None, **kw: Any)

    Construct a new `AsyncSession`.

    All parameters other than `sync_session_class` are passed to the `sync_session_class` callable directly to instantiate a new `Session`. Refer to `Session.__init__()` for parameter documentation.

    Parameters:

      sync_session_class –

      A `Session` subclass or other callable which will be used to construct the `Session` which will be proxied. This parameter may be used to provide custom `Session` subclasses. Defaults to the `AsyncSession.sync_session_class` class-level attribute.

      Added in version 1.4.24.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async aclose() → None

    A synonym for `AsyncSession.close()`.

    The `AsyncSession.aclose()` name is specifically to support the Python standard library `@contextlib.aclosing` context manager function.

    Added in version 2.0.20.

  method `sqlalchemy.ext.asyncio.AsyncSession.` add(instance: object, _warn: bool = True) → None

    Place an object into this `Session`.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Objects that are in the transient state when passed to the `Session.add()` method will move to the pending state, until the next flush, at which point they will move to the persistent state.

    Objects that are in the detached state when passed to the `Session.add()` method will move to the persistent state directly.

    If the transaction used by the `Session` is rolled back, objects which were transient when they were passed to `Session.add()` will be moved back to the transient state, and will no longer be present within this `Session`.

    See also

    `Session.add_all()`

    Adding New or Existing Items - at Basics of Using a Session

  method `sqlalchemy.ext.asyncio.AsyncSession.` add_all(instances: Iterable[object]) → None

    Add the given collection of instances to this `Session`.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    See the documentation for `Session.add()` for a general behavioral description.

    See also

    `Session.add()`

    Adding New or Existing Items - at Basics of Using a Session

  property autoflush: bool

    Proxy for the `Session.autoflush` attribute on behalf of the `AsyncSession` class.

  method `sqlalchemy.ext.asyncio.AsyncSession.` begin() → AsyncSessionTransaction

    Return an `AsyncSessionTransaction` object.

    The underlying `Session` will perform the “begin” action when the `AsyncSessionTransaction` object is entered:

        async with async_session.begin():
            ...  # ORM transaction is begun

    Note that database IO will not normally occur when the session-level transaction is begun, as database transactions begin on an on-demand basis. However, the begin block is async to accommodate for a `SessionEvents.after_transaction_create()` event hook that may perform IO.

    For a general description of ORM begin, see `Session.begin()`.

  method `sqlalchemy.ext.asyncio.AsyncSession.` begin_nested() → AsyncSessionTransaction

    Return an `AsyncSessionTransaction` object which will begin a “nested” transaction, e.g. SAVEPOINT.

    Behavior is the same as that of `AsyncSession.begin()`.

    For a general description of ORM begin nested, see `Session.begin_nested()`.

    See also

    Serializable isolation / Savepoints / Transactional DDL (asyncio version) - special workarounds required with the SQLite asyncio driver in order for SAVEPOINT to work correctly.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async close() → None

    Close out the transactional resources and ORM objects used by this `AsyncSession`.

    See also

    `Session.close()` - main documentation for “close”

    Closing - detail on the semantics of `AsyncSession.close()` and `AsyncSession.reset()`.

  async classmethod `sqlalchemy.ext.asyncio.AsyncSession.` close_all() → None

    Close all `AsyncSession` sessions.

    Deprecated since version 2.0: The `AsyncSession.close_all()` method is deprecated and will be removed in a future release. Please refer to `close_all_sessions()`.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async commit() → None

    Commit the current transaction in progress.

    See also

    `Session.commit()` - main documentation for “commit”

  method `sqlalchemy.ext.asyncio.AsyncSession.` async connection(bind_arguments: _BindArguments | None = None, execution_options: CoreExecuteOptionsParameter | None = None, **kw: Any) → AsyncConnection

    Return a `AsyncConnection` object corresponding to this `Session` object’s transactional state.

    This method may also be used to establish execution options for the database connection used by the current transaction.

    Added in version 1.4.24: Added **kw arguments which are passed through to the underlying `Session.connection()` method.

    See also

    `Session.connection()` - main documentation for “connection”

  method `sqlalchemy.ext.asyncio.AsyncSession.` async delete(instance: object) → None

    Mark an instance as deleted.

    The database delete operation occurs upon `flush()`.

    As this operation may need to cascade along unloaded relationships, it is awaitable to allow for those queries to take place.

    See also

    `Session.delete()` - main documentation for delete

  property deleted: Any

    The set of all instances marked as ‘deleted’ within this `Session`

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

  property dirty: Any

    The set of all persistent instances considered dirty.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    E.g.:

        some_mapped_object in session.dirty

    Instances are considered dirty when they were modified but not deleted.

    Note that this ‘dirty’ calculation is ‘optimistic’; most attribute-setting or collection modification operations will mark an instance as ‘dirty’ and place it in this set, even if there is no net change to the attribute’s value. At flush time, the value of each attribute is compared to its previously saved value, and if there’s no net change, no SQL operation will occur (this is a more expensive operation so it’s only done at flush time).

    To check if an instance has actionable net changes to its attributes, use the `Session.is_modified()` method.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async execute(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → Result[Any]

    Execute a statement and return a buffered `Result` object.

    See also

    `Session.execute()` - main documentation for execute

  method `sqlalchemy.ext.asyncio.AsyncSession.` expire(instance: object, attribute_names: Iterable[str] | None = None) → None

    Expire the attributes on an instance.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Marks the attributes of an instance as out of date. When an expired attribute is next accessed, a query will be issued to the `Session` object’s current transactional context in order to load all expired attributes for the given instance. Note that a highly isolated transaction will return the same values as were previously read in that same transaction, regardless of changes in database state outside of that transaction.

    To expire all objects in the `Session` simultaneously, use `Session.expire_all()`.

    The `Session` object’s default behavior is to expire all state whenever the `Session.rollback()` or `Session.commit()` methods are called, so that new state can be loaded for the new transaction. For this reason, calling `Session.expire()` only makes sense for the specific case that a non-ORM SQL statement was emitted in the current transaction.

    Parameters:

      - instance – The instance to be refreshed.

      - attribute_names – optional list of string attribute names indicating a subset of attributes to be expired.

    See also

    Refreshing / Expiring - introductory material

    `Session.expire()`

    `Session.refresh()`

    `Query.populate_existing()`

  method `sqlalchemy.ext.asyncio.AsyncSession.` expire_all() → None

    Expires all persistent instances within this Session.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    When any attributes on a persistent instance is next accessed, a query will be issued using the `Session` object’s current transactional context in order to load all expired attributes for the given instance. Note that a highly isolated transaction will return the same values as were previously read in that same transaction, regardless of changes in database state outside of that transaction.

    To expire individual objects and individual attributes on those objects, use `Session.expire()`.

    The `Session` object’s default behavior is to expire all state whenever the `Session.rollback()` or `Session.commit()` methods are called, so that new state can be loaded for the new transaction. For this reason, calling `Session.expire_all()` is not usually needed, assuming the transaction is isolated.

    See also

    Refreshing / Expiring - introductory material

    `Session.expire()`

    `Session.refresh()`

    `Query.populate_existing()`

  method `sqlalchemy.ext.asyncio.AsyncSession.` expunge(instance: object) → None

    Remove the instance from this `Session`.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This will free all internal references to the instance. Cascading will be applied according to the expunge cascade rule.

  method `sqlalchemy.ext.asyncio.AsyncSession.` expunge_all() → None

    Remove all object instances from this `Session`.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This is equivalent to calling `expunge(obj)` on all objects in this `Session`.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async flush(objects: Sequence[Any] | None = None) → None

    Flush all the object changes to the database.

    See also

    `Session.flush()` - main documentation for flush

  method `sqlalchemy.ext.asyncio.AsyncSession.` async get(entity: _EntityBindKey[_O], ident: _PKIdentityArgument, *, options: Sequence[ORMOption] | None = None, populate_existing: bool = False, with_for_update: ForUpdateParameter = None, identity_token: Any | None = None, execution_options: OrmExecuteOptionsParameter = {}) → _O | None

    Return an instance based on the given primary key identifier, or `None` if not found.

    See also

    `Session.get()` - main documentation for get

  method `sqlalchemy.ext.asyncio.AsyncSession.` get_bind(mapper: _EntityBindKey[_O] | None = None, clause: ClauseElement | None = None, bind: _SessionBind | None = None, **kw: Any) → Engine | Connection

    Return a “bind” to which the synchronous proxied `Session` is bound.

    Unlike the `Session.get_bind()` method, this method is currently not used by this `AsyncSession` in any way in order to resolve engines for requests.

    Note

    This method proxies directly to the `Session.get_bind()` method, however is currently not useful as an override target, in contrast to that of the `Session.get_bind()` method. The example below illustrates how to implement custom `Session.get_bind()` schemes that work with `AsyncSession` and `AsyncEngine`.

    The pattern introduced at Custom Vertical Partitioning illustrates how to apply a custom bind-lookup scheme to a `Session` given a set of `Engine` objects. To apply a corresponding `Session.get_bind()` implementation for use with a `AsyncSession` and `AsyncEngine` objects, continue to subclass `Session` and apply it to `AsyncSession` using `AsyncSession.sync_session_class`. The inner method must continue to return `Engine` instances, which can be acquired from a `AsyncEngine` using the `AsyncEngine.sync_engine` attribute:

        # using example from "Custom Vertical Partitioning"

        import random

        from sqlalchemy.ext.asyncio import AsyncSession
        from sqlalchemy.ext.asyncio import create_async_engine
        from sqlalchemy.ext.asyncio import async_sessionmaker
        from sqlalchemy.orm import Session

        # construct async engines w/ async drivers
        engines = {
            "leader": create_async_engine("sqlite+aiosqlite:///leader.db"),
            "other": create_async_engine("sqlite+aiosqlite:///other.db"),
            "follower1": create_async_engine("sqlite+aiosqlite:///follower1.db"),
            "follower2": create_async_engine("sqlite+aiosqlite:///follower2.db"),
        }

        class RoutingSession(Session):
            def get_bind(self, mapper=None, clause=None, **kw):
                # within get_bind(), return sync engines
                if mapper and issubclass(mapper.class_, MyOtherClass):
                    return engines["other"].sync_engine
                elif self._flushing or isinstance(clause, (Update, Delete)):
                    return engines["leader"].sync_engine
                else:
                    return engines[
                        random.choice(["follower1", "follower2"])
                    ].sync_engine

        # apply to AsyncSession using sync_session_class
        AsyncSessionMaker = async_sessionmaker(sync_session_class=RoutingSession)

    The `Session.get_bind()` method is called in a non-asyncio, implicitly non-blocking context in the same manner as ORM event hooks and functions that are invoked via `AsyncSession.run_sync()`, so routines that wish to run SQL commands inside of `Session.get_bind()` can continue to do so using blocking-style code, which will be translated to implicitly async calls at the point of invoking IO on the database drivers.

  method `sqlalchemy.ext.asyncio.AsyncSession.` get_nested_transaction() → AsyncSessionTransaction | None

    Return the current nested transaction in progress, if any.

    Returns:

      an `AsyncSessionTransaction` object, or `None`.

    Added in version 1.4.18.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async get_one(entity: _EntityBindKey[_O], ident: _PKIdentityArgument, *, options: Sequence[ORMOption] | None = None, populate_existing: bool = False, with_for_update: ForUpdateParameter = None, identity_token: Any | None = None, execution_options: OrmExecuteOptionsParameter = {}) → _O

    Return an instance based on the given primary key identifier, or raise an exception if not found.

    Raises `NoResultFound` if the query selects no rows.

    ..versionadded: 2.0.22

    See also

    `Session.get_one()` - main documentation for get_one

  method `sqlalchemy.ext.asyncio.AsyncSession.` get_transaction() → AsyncSessionTransaction | None

    Return the current root transaction in progress, if any.

    Returns:

      an `AsyncSessionTransaction` object, or `None`.

    Added in version 1.4.18.

  classmethod `sqlalchemy.ext.asyncio.AsyncSession.` identity_key(class_: Type[Any] | None = None, ident: Any | Tuple[Any, ...] = None, *, instance: Any | None = None, row: Row[Any] | RowMapping | None = None, identity_token: Any | None = None) → _IdentityKeyType[Any]

    Return an identity key.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This is an alias of `identity_key()`.

  property identity_map: IdentityMap

    Proxy for the `Session.identity_map` attribute on behalf of the `AsyncSession` class.

  method `sqlalchemy.ext.asyncio.AsyncSession.` in_nested_transaction() → bool

    Return True if this `Session` has begun a nested transaction, e.g. SAVEPOINT.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Added in version 1.4.

  method `sqlalchemy.ext.asyncio.AsyncSession.` in_transaction() → bool

    Return True if this `Session` has begun a transaction.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Added in version 1.4.

    See also

    `Session.is_active`

  property info: Any

    A user-modifiable dictionary.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    The initial value of this dictionary can be populated using the `info` argument to the `Session` constructor or `sessionmaker` constructor or factory methods. The dictionary here is always local to this `Session` and can be modified independently of all other `Session` objects.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async invalidate() → None

    Close this Session, using connection invalidation.

    For a complete description, see `Session.invalidate()`.

  property is_active: Any

    True if this `Session` not in “partial rollback” state.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    Changed in version 1.4: The `Session` no longer begins a new transaction immediately, so this attribute will be False when the `Session` is first instantiated.

    “partial rollback” state typically indicates that the flush process of the `Session` has failed, and that the `Session.rollback()` method must be emitted in order to fully roll back the transaction.

    If this `Session` is not in a transaction at all, the `Session` will autobegin when it is first used, so in this case `Session.is_active` will return True.

    Otherwise, if this `Session` is within a transaction, and that transaction has not been rolled back internally, the `Session.is_active` will also return True.

    See also

    “This Session’s transaction has been rolled back due to a previous exception during flush.” (or similar)

    `Session.in_transaction()`

  method `sqlalchemy.ext.asyncio.AsyncSession.` is_modified(instance: object, include_collections: bool = True) → bool

    Return `True` if the given instance has locally modified attributes.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This method retrieves the history for each instrumented attribute on the instance and performs a comparison of the current value to its previously flushed or committed value, if any.

    It is in effect a more expensive and accurate version of checking for the given instance in the `Session.dirty` collection; a full test for each attribute’s net “dirty” status is performed.

    E.g.:

        return session.is_modified(someobject)

    A few caveats to this method apply:

    - Instances present in the `Session.dirty` collection may report `False` when tested with this method. This is because the object may have received change events via attribute mutation, thus placing it in `Session.dirty`, but ultimately the state is the same as that loaded from the database, resulting in no net change here.

    - Scalar attributes may not have recorded the previously set value when a new value was applied, if the attribute was not loaded, or was expired, at the time the new value was received - in these cases, the attribute is assumed to have a change, even if there is ultimately no net change against its database value. SQLAlchemy in most cases does not need the “old” value when a set event occurs, so it skips the expense of a SQL call if the old value isn’t present, based on the assumption that an UPDATE of the scalar value is usually needed, and in those few cases where it isn’t, is less expensive on average than issuing a defensive SELECT.

      The “old” value is fetched unconditionally upon set only if the attribute container has the `active_history` flag set to `True`. This flag is set typically for primary key attributes and scalar object references that are not a simple many-to-one. To set this flag for any arbitrary mapped column, use the `active_history` argument with `column_property()`.

    Parameters:

      - instance – mapped instance to be tested for pending changes.

      - include_collections – Indicates if multivalued collections should be included in the operation. Setting this to `False` is a way to detect only local-column based properties (i.e. scalar columns or many-to-one foreign keys) that would result in an UPDATE for this instance upon flush.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async merge(instance: _O, *, load: bool = True, options: Sequence[ORMOption] | None = None) → _O

    Copy the state of a given instance into a corresponding instance within this `AsyncSession`.

    See also

    `Session.merge()` - main documentation for merge

  property new: Any

    The set of all instances marked as ‘new’ within this `Session`.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

  property no_autoflush: Any

    Return a context manager that disables autoflush.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    e.g.:

        with session.no_autoflush:

            some_object = SomeClass()
            session.add(some_object)
            # won't autoflush
            some_object.related_thing = session.query(SomeRelated).first()

    Operations that proceed within the `with:` block will not be subject to flushes occurring upon query access. This is useful when initializing a series of objects which involve existing database queries, where the uncompleted object should not yet be flushed.

  classmethod `sqlalchemy.ext.asyncio.AsyncSession.` object_session(instance: object) → Session | None

    Return the `Session` to which an object belongs.

    Proxied for the `Session` class on behalf of the `AsyncSession` class.

    This is an alias of `object_session()`.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async refresh(instance: object, attribute_names: Iterable[str] | None = None, with_for_update: ForUpdateParameter = None) → None

    Expire and refresh the attributes on the given instance.

    A query will be issued to the database and all attributes will be refreshed with their current database value.

    This is the async version of the `Session.refresh()` method. See that method for a complete description of all options.

    See also

    `Session.refresh()` - main documentation for refresh

  method `sqlalchemy.ext.asyncio.AsyncSession.` async reset() → None

    Close out the transactional resources and ORM objects used by this `Session`, resetting the session to its initial state.

    Added in version 2.0.22.

    See also

    `Session.reset()` - main documentation for “reset”

    Closing - detail on the semantics of `AsyncSession.close()` and `AsyncSession.reset()`.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async rollback() → None

    Rollback the current transaction in progress.

    See also

    `Session.rollback()` - main documentation for “rollback”

  method `sqlalchemy.ext.asyncio.AsyncSession.` async run_sync(fn: ~typing.Callable[[~typing.Concatenate[~sqlalchemy.orm.session.Session, ~_P]], ~sqlalchemy.ext.asyncio.session._T], *arg: ~typing.~_P, **kw: ~typing.~_P) → _T

    Invoke the given synchronous (i.e. not async) callable, passing a synchronous-style `Session` as the first argument.

    This method allows traditional synchronous SQLAlchemy functions to run within the context of an asyncio application.

    E.g.:

        def some_business_method(session: Session, param: str) -> str:
            """A synchronous function that does not require awaiting

            :param session: a SQLAlchemy Session, used synchronously

            :return: an optional return value is supported

            """
            session.add(MyObject(param=param))
            session.flush()
            return "success"

        async def do_something_async(async_engine: AsyncEngine) -> None:
            """an async function that uses awaiting"""

            with AsyncSession(async_engine) as async_session:
                # run some_business_method() with a sync-style
                # Session, proxied into an awaitable
                return_code = await async_session.run_sync(
                    some_business_method, param="param1"
                )
                print(return_code)

    This method maintains the asyncio event loop all the way through to the database connection by running the given callable in a specially instrumented greenlet.

    Tip

    The provided callable is invoked inline within the asyncio event loop, and will block on traditional IO calls. IO within this callable should only call into SQLAlchemy’s asyncio database APIs which will be properly adapted to the greenlet context.

    See also

    `AsyncAttrs` - a mixin for ORM mapped classes that provides a similar feature more succinctly on a per-attribute basis

    `AsyncConnection.run_sync()`

    Running Synchronous Methods and Functions under asyncio

  method `sqlalchemy.ext.asyncio.AsyncSession.` async scalar(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → Any

    Execute a statement and return a scalar result.

    See also

    `Session.scalar()` - main documentation for scalar

  method `sqlalchemy.ext.asyncio.AsyncSession.` async scalars(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → ScalarResult[Any]

    Execute a statement and return scalar results.

    Returns:

      a `ScalarResult` object

    Added in version 1.4.24: Added `AsyncSession.scalars()`

    Added in version 1.4.26: Added `async_scoped_session.scalars()`

    See also

    `Session.scalars()` - main documentation for scalars

    `AsyncSession.stream_scalars()` - streaming version

  method `sqlalchemy.ext.asyncio.AsyncSession.` async stream(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → AsyncResult[Any]

    Execute a statement and return a streaming `AsyncResult` object.

  method `sqlalchemy.ext.asyncio.AsyncSession.` async stream_scalars(statement: Executable, params: _CoreAnyExecuteParams | None = None, *, execution_options: OrmExecuteOptionsParameter = {}, bind_arguments: _BindArguments | None = None, **kw: Any) → AsyncScalarResult[Any]

    Execute a statement and return a stream of scalar results.

    Returns:

      an `AsyncScalarResult` object

    Added in version 1.4.24.

    See also

    `Session.scalars()` - main documentation for scalars

    `AsyncSession.scalars()` - non streaming version

  attribute `sqlalchemy.ext.asyncio.AsyncSession.` sync_session: Session

    Reference to the underlying `Session` this `AsyncSession` proxies requests towards.

    This instance can be used as an event target.

    See also

    Using events with the asyncio extension

  attribute `sqlalchemy.ext.asyncio.AsyncSession.` sync_session_class: Type[Session]

    The class or callable that provides the underlying `Session` instance for a particular `AsyncSession`.

    At the class level, this attribute is the default value for the `AsyncSession.sync_session_class` parameter. Custom subclasses of `AsyncSession` can override this.

    At the instance level, this attribute indicates the current class or callable that was used to provide the `Session` instance for this `AsyncSession` instance.

    Added in version 1.4.24.

class sqlalchemy.ext.asyncio.AsyncSessionTransaction

  inherits from `sqlalchemy.ext.asyncio.base.ReversibleProxy`, `sqlalchemy.ext.asyncio.base.StartableContext`

  A wrapper for the ORM `SessionTransaction` object.

  This object is provided so that a transaction-holding object for the `AsyncSession.begin()` may be returned.

  The object supports both explicit calls to `AsyncSessionTransaction.commit()` and `AsyncSessionTransaction.rollback()`, as well as use as an async context manager.

  Added in version 1.4.

  Member Name | Description
  --- | ---
  commit() | Commit this `AsyncTransaction`.
  rollback() | Roll back this `AsyncTransaction`.

  method `sqlalchemy.ext.asyncio.AsyncSessionTransaction.` async commit() → None

    Commit this `AsyncTransaction`.

  method `sqlalchemy.ext.asyncio.AsyncSessionTransaction.` async rollback() → None

    Roll back this `AsyncTransaction`.