👀 Views: 42 💬 Answers: 1 📅 Created: 2025-06-04

python fastapi sqlalchemy asyncio Python

This might be a silly question, but I'm working on a FastAPI application where I'm trying to perform async database operations using SQLAlchemy 1.4 and `asyncpg` for PostgreSQL. However, I'm working with a `TypeError` when attempting to execute a query against the database. The behavior message states: `TypeError: 'coroutine' object is not subscriptable`. Here's a snippet of my code: ```python import asyncio from fastapi import FastAPI from sqlalchemy.ext.asyncio import AsyncSession, create_async_engine from sqlalchemy.orm import sessionmaker from sqlalchemy.future import select DATABASE_URL = "postgresql+asyncpg://user:password@localhost/db_name" engine = create_async_engine(DATABASE_URL, echo=True) session_local = sessionmaker(engines, class_=AsyncSession, expire_on_commit=False) app = FastAPI() async def get_db(): async with session_local() as session: yield session @app.get("/items/{item_id}") async def read_item(item_id: int, db: AsyncSession = Depends(get_db)): query = select(Item).where(Item.id == item_id) result = await db.execute(query) return result.scalars().first() ``` I've made sure that my async session is correctly set up, but the behavior appears when I try to access the result object. I have also tried using `await` on the `db.execute(query)` line, expecting it to return a usable result. I've gone through multiple examples on the FastAPI documentation and various blog posts, but nothing seems to resolve this scenario. Could anyone provide insights on why this behavior might be happening and how to correctly fetch the result from the async database operation? I'm using FastAPI version 0.68.0 and SQLAlchemy version 1.4.22. This is part of a larger CLI tool I'm building.