fastapi-patterns

Topics in the source

• FastAPI Patterns
• Project Structure
• App Factory and Lifespan
• Configuration with pydantic-settings
• Pydantic Schemas (v2)
• Dependency Injection
• Router and Endpoint Design
• Service Layer

Modern, production-grade FastAPI development: project layout, Pydantic v2 schemas, dependency injection, async patterns, auth, transactional service methods, and testing. -- -- -- -- -- -- Note on Database Design: Application-level unique handling requires an underlying unique database index (e.g., unique=True on your SQLAlchemy mapping attributes). Without underlying constraints, application layer error-catching cannot safely prevent concurrent race conditions. -- -- -- Always declare a typed responsemodel to prevent accidental PII/data leaks and output clean OpenAPI schemas. Consolidate standard middleware dependency injections via type-aliasing: DbDep = Annotated[AsyncSession, Depends(getdb)]. Wrap database mutation boundaries gracefully within transactions inside your service layer, catching structural database errors directly. Parse JWT parameters defensively, expecting potential string/integer cast mismatches from modern payload variations. Enforce deterministic sorting (e.g., .orderby(Model.id)) on all offset/limit paginated endpoints to avoid data skips. Isolate authorization checks from core authentication dependencies to provide precise REST status signals (401 vs 403).