SQLAlchemy 1.4 异步事件监听器答案

【问题标题】：SQLAlchemy 1.4 async event listenersSQLAlchemy 1.4 异步事件监听器
【发布时间】：2021-06-07 15:02:30
【问题描述】：

尝试使用事件监听器(https://docs.sqlalchemy.org/en/14/core/events.html#sqlalchemy.events.ConnectionEvents ) 在异步 sqlalchemy 引擎上并收到此错误： {NotImplementedError}asynchronous events are not implemented at this time. Apply synchronous listeners to the AsyncEngine.sync_engine or AsyncConnection.sync_connection attributes.

如果我理解正确，我不能在异步引擎上使用事件，如果我想要事件支持，我必须切换到同步引擎？

engine: Engine = create_async_engine(
    URL, echo=True, future=True
)

async_session = sessionmaker(
    engine, class_=AsyncSession, expire_on_commit=False, future=True
)


event.listens_for(engine, "do_connect")(do_connect_listener)
event.listens_for(engine, "engine_connect")(engine_connect_listener)

【问题讨论】：

标签： sqlalchemy

【解决方案1】：

从 github 上的 SQLAlchemy 讨论部分得到了答案。所有功劳归于 OP(https://github.com/sqlalchemy/sqlalchemy/discussions/6594#discussioncomment-836437)：

“嗨，

正如异常所建议的，您可以在应用事件时使用 sync_engine/sync_connection。下面是一个例子："



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

engine = create_async_engine("sqlite+aiosqlite:///:memory:")

@event.listens_for(engine.sync_engine, "do_connect")
def do_connect(dialect, conn_rec, cargs, cparams):
    print("some-function")

@event.listens_for(engine.sync_engine, "engine_connect")
def engine_connect(conn, branch):
    print("engine_connect", conn.exec_driver_sql("select 1").scalar())

async def go():
    async with engine.connect() as conn:
        res = await conn.exec_driver_sql("select 2")
        print("go", res.scalar())

asyncio.run(go())

【讨论】：