fastapi-patterns

Structure your FastAPI app with organized directories for routes, models, and services. Use dependency injection for modularity, apply strict type hints throughout, leverage Pydantic for data validation, and implement async patterns for IO-bound operations to create maintainable, scalable applications.

Implement JWT authentication patterns in FastAPI by validating tokens through dependency injection, storing credentials securely, and protecting endpoints with auth guards. This approach integrates with FastAPI's security utilities and maintains async performance.

Test FastAPI apps by creating scaffolds with async test fixtures, mocking dependencies, and validating endpoints end-to-end. Use dependency injection to swap real services with test doubles, ensuring your async handlers and Pydantic models behave correctly.

Yes, FastAPI is async by default. Design your entire application with async functions, including route handlers, database access, and external API calls. This maximizes throughput for IO-bound workloads and pairs seamlessly with Pydantic validation.

Dependency injection in FastAPI enables reusable, testable, and loosely-coupled components. Declare dependencies in function signatures; FastAPI automatically resolves and injects them, simplifying authentication, database connections, and service layer integration.

FastAPI automatically generates OpenAPI docs from your type hints and Pydantic models, creating interactive API documentation. This eliminates manual docs, enables client generation, and serves as a contract for your API's structure and behavior.