FastAPI / Modern Python API

When to use this skill

• Building high-performance APIs with FastAPI.

• Defining Pydantic models.

• Structuring API projects.

1. Structure

• Routers: Split routes into modules (app/routers/users.py ) and include them in main.py .

• Dependencies: Use Dependency Injection (Depends() ) for DB sessions, auth, and shared logic.

2. Pydantic Models

• Separation: Create separate models for Input (UserCreate ), Output (UserResponse ), and Database (UserDB ).

• Validation: Use strict Types and Field(...) for validation metadata.

3. Async

• Def vs Async Def: Use async def for endpoints that await I/O (DB, HTTP). Use def only if blocking CPU.