fastapi-patterns

Organize FastAPI routes by splitting them into APIRouter modules by domain, then compose them in the main app with prefixes and tags. This structure maintains clear endpoint separation and scalable code organization across large projects.

The best way to handle FastAPI dependency injection is using Depends() explicitly for database sessions, auth, config, and shared logic. This avoids global state and ensures clear type contracts and maintainable endpoint wiring.

Use async def in FastAPI routing for I/O-bound routes with async drivers, and use plain def for CPU-bound or sync-only code. Leveraging async where it matters ensures robust API performance without blocking the event loop.

Pydantic models act as the single source of truth for request and response schemas in FastAPI. Define these models explicitly and avoid raw dicts in route signatures to ensure OpenAPI-compatible schemas and clear type contracts.

This approach applies to projects listing FastAPI in their dependencies. It enforces explicit dependency injection and Pydantic models to satisfy requirements for structured code organization and maintainable endpoints.

Avoid global state in FastAPI applications to maintain explicit dependency injection and clear type contracts. Using Depends() for shared logic and configuration ensures your API endpoints remain robust, scalable, and maintainable.