FastAPI Best Practices

Project Structure

• app/main.py - Application entry

• app/routers/ - Route handlers

• app/models/ - SQLAlchemy models

• app/schemas/ - Pydantic schemas

• app/services/ - Business logic

• app/dependencies.py - Dependency injection

Pydantic Schemas

• Use separate schemas for input/output

• Use Field() for validation

• Use model_validator for complex validation

• Use Config for schema settings

Dependency Injection

• Use Depends() for dependencies

• Create reusable dependencies

• Use yield for cleanup logic

• Cache expensive dependencies

Async

• Use async def for I/O operations

• Use httpx for async HTTP

• Use databases/SQLAlchemy async

• Avoid blocking in async context

Performance

• Use response_model for serialization

• Enable response caching

• Use background tasks

• Stream large responses

• Use connection pooling