FastAPI Best Practices
4 min read Quiz at the end
Best practices: response_model, Depends(), async for I/O, APIRouter, Alembic migrations.
FastAPI Best Practices
- Always use
response_model to control what data is returned - Use
Depends() for DB sessions, auth, and shared logic - Validate all input with Pydantic models — never trust raw input
- Use
async def for I/O-bound endpoints (DB, HTTP calls) - Use
def for CPU-bound operations (FastAPI runs in threadpool) - Use
APIRouter to split large apps into modules - Add
tags= and description= for better auto-docs - Use Alembic for database migrations with SQLAlchemy
- Write tests with
TestClient - Use
lifespan for startup/shutdown instead of deprecated events
Topic Quiz · 2 questions
Test your understanding before moving on
1. Why use async def endpoints in FastAPI?
💡 async def allows FastAPI to handle other requests while waiting for I/O.
2. When should you use def (sync) instead of async def?
💡 FastAPI runs sync endpoints in a threadpool keeping async endpoints non-blocking.