Sharing Logic Across Endpoints with FastAPI Dependency Injection

A practical FastAPI dependency injection tutorial that builds an article API and factors its cross-cutting concerns into dependencies. Covers Depends for injecting shared logic, dependencies with validated Query and Header parameters for pagination and authentication, raising HTTPException to short-circuit unauthorized requests with a 401, resolving multiple dependencies per endpoint, and yield dependencies for opening and reliably closing per-request database sessions. Essential for building maintainable FastAPI services without duplicated boilerplate.