Handling asyncio and SQLAlchemy session management in FastAPI - SessionClosedError
After trying multiple solutions online, I still can't figure this out. I'm working on a FastAPI application that uses SQLAlchemy for database interactions and asyncio for handling requests. I am working with a `SessionClosedError` when I try to access the database within a route handler that is async. My code looks like this: ```python from fastapi import FastAPI, Depends from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine from sqlalchemy.orm import sessionmaker from sqlalchemy.ext.declarative import declarative_base DATABASE_URL = 'postgresql+asyncpg://user:password@localhost/dbname' engine = create_async_engine(DATABASE_URL, echo=True) Base = declarative_base() async_session = sessionmaker(engine, class_=AsyncSession, expire_on_commit=False) app = FastAPI() async def get_db() -> AsyncSession: async with async_session() as session: yield session @app.get('/items/{item_id}') async def read_item(item_id: int, db: AsyncSession = Depends(get_db)): # Simulating a db query that might cause the behavior async with db.begin(): # Starting a transaction result = await db.execute('SELECT * FROM items WHERE id = :id', {'id': item_id}) item = result.fetchone() return item ``` When I make a GET request to `/items/1`, I receive the following behavior: ``` sqlalchemy.exc.SessionClosedError: This Session is closed ``` I believe the scenario might be related to the context in which the database session is being accessed, but I'm unsure how to properly manage the session lifecycles with FastAPI's async capabilities. I've tried various configurations for session management, including adjusting the `async_session` settings, but nothing seems to resolve the scenario. Any insights or best practices for handling SQLAlchemy sessions with FastAPI async routes would be greatly appreciated. I'm working on a CLI tool that needs to handle this. Is there a better approach? How would you solve this?