FastAPI Async Function Not Awaiting Database Query Using SQLAlchemy
I recently switched to I'm prototyping a solution and I can't seem to get I'm sure I'm missing something obvious here, but I'm working on a personal project and I'm sure I'm missing something obvious here, but I'm working on a FastAPI application where I'm trying to fetch data from a PostgreSQL database using SQLAlchemy..... However, I'm working with an scenario where my async function does not seem to be awaiting the database query correctly. This leads to unexpected behavior in my API responses. I'm using SQLAlchemy 1.4 with async support enabled, and FastAPI version 0.68.1. Here’s the relevant part of my code: ```python from fastapi import FastAPI, HTTPException from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine from sqlalchemy.ext.declarative import declarative_base from sqlalchemy.orm import sessionmaker from sqlalchemy.future import select DATABASE_URL = "postgresql+asyncpg://user:password@localhost/dbname" engine = create_async_engine(DATABASE_URL, echo=True) AsyncSessionLocal = sessionmaker(bind=engine, class_=AsyncSession, expire_on_commit=False) Base = declarative_base() class Item(Base): __tablename__ = "items" id = Column(Integer, primary_key=True, index=True) name = Column(String, index=True) app = FastAPI() @app.get("/items/{item_id}") async def read_item(item_id: int): async with AsyncSessionLocal() as session: result = await session.execute(select(Item).where(Item.id == item_id)) item = result.scalars().first() if item is None: raise HTTPException(status_code=404, detail="Item not found") return item ``` When I call the endpoint `/items/1`, it sometimes returns an empty object instead of raising a 404 behavior, even though I know there is an item with that ID in the database. I suspect that the scenario may be related to how I’m handling the session or the query, but after trying various approaches, including using `await` correctly, I still can’t identify the question. I’ve checked the database connection and confirmed that the item exists by querying directly using `psql`. I also added some logging, and the SQL statements being generated seem to be correct. However, the behavior can be inconsistent, leading me to believe there’s a race condition or some mismanagement of the session lifecycle. Has anyone experienced something similar, or can anyone point out what I might be missing in this async context? I'd really appreciate any guidance on this. For context: I'm using Python on Ubuntu. I'd really appreciate any guidance on this. This is part of a larger API I'm building. What am I doing wrong? Thanks for your help in advance! Any ideas what could be causing this?