Sqlalchemy 事件循环已关闭

Question

我正在摆弄 sqlalchemy ORM 功能

我能够使其在我的主应用程序上运行，但是当我创建一个单独的文件test.py来测试某些内容时，我不断收到事件循环关闭错误：

Exception ignored in: <function Connection.__del__ at 0x7f7041c07310>
Traceback (most recent call last):
  File "/home/krypt/Documents/Projects/app/env/lib/python3.9/site-packages/aiomysql/connection.py", line 1072, in __del__
  File "/home/krypt/Documents/Projects/app/env/lib/python3.9/site-packages/aiomysql/connection.py", line 298, in close
  File "/usr/lib/python3.9/asyncio/selector_events.py", line 700, in close
  File "/usr/lib/python3.9/asyncio/base_events.py", line 746, in call_soon
  File "/usr/lib/python3.9/asyncio/base_events.py", line 510, in _check_closed
RuntimeError: Event loop is closed

这是代码test.py：

from sqlalchemy.ext.asyncio import create_async_engine
from sqlalchemy.orm import declarative_base
from sqlalchemy.orm import sessionmaker
from sqlalchemy.ext.asyncio import AsyncSession
from sqlalchemy import Table, Column, Integer, String
from sqlalchemy.future import select
from sqlalchemy import delete
import asyncio

Base = declarative_base()

class Table(Base):
    __tablename__ = 'Table'

    id = Column(Integer, primary_key=True)
    string = Column(String(30))
    prefix = Column(String(1), default = "!")




async def main():
    engine = create_async_engine("mariadb+aiomysql://user:password@127.0.0.1:3306/dbname")
    session = AsyncSession(engine)

    stmt = select(Table).where(Table.prefix == "!")

    res = await session.execute(stmt)
    row = res.scalars().first()

    print(row)

asyncio.run(main())

Answer 1

问题似乎是 aiomysql 试图在事件循环关闭后关闭其连接。我可以通过确保会话关闭并处理引擎来使问题中的代码正常工作。

async def main():
    engine = create_async_engine("mariadb+aiomysql://user:password@127.0.0.1:3306/dbname")
    async with AsyncSession(engine) as session:

        stmt = select(Table).where(Table.prefix == "!")

        res = await session.execute(stmt)
        row = res.scalars().first()

        print(row)
    await engine.dispose()

这里有一些关于这个的讨论（接近尾声）；__del__显式关闭和处置是建议的解决方法，以防止在事件循环关闭后执行连接的方法。