FastAPI architecture recommended
Dependency Injection Patterns
FastAPI dependency injection patterns including caching, lifespan management, yield dependencies for cleanup, and testing overrides.
- Difficulty
- intermediate
- Read time
- 1 min read
- Version
- v1.0.0
- Confidence
- established
- Last updated
Quick Reference
Use Depends() for dependency injection. Dependencies are cached per-request by default. Use yield for cleanup (DB sessions, file handles). Use lifespan context manager for startup/shutdown (connection pools). Chain dependencies for authentication/authorization. Override dependencies in tests with app.dependency_overrides.
Use When
- Setting up database connections
- Implementing authentication
- Managing shared resources
- Testing FastAPI applications
Skip When
- Simple endpoints without shared state
- Single-file scripts
Dependency Injection Patterns
FastAPI dependency injection patterns including caching, lifespan management, yield dependencies for cleanup, and testing overrides.