graph LR
Router_Route_Manager["Router/Route Manager"]
Dependency_Resolver["Dependency Resolver"]
Dependency_Declaration["Dependency Declaration"]
Security_Dependency_Handler["Security Dependency Handler"]
Router_Route_Manager -- "configures" --> Dependency_Resolver
Router_Route_Manager -- "delegates processing to" --> Dependency_Resolver
Dependency_Resolver -- "processes" --> Dependency_Declaration
Dependency_Resolver -- "invokes" --> Security_Dependency_Handler
Dependency_Declaration -- "declares" --> Security_Dependency_Handler
The Request Processing & Routing subsystem in FastAPI is responsible for the initial handling of incoming HTTP requests. Its boundaries encompass: Route Definition and Matching, Parameter Parsing and Validation, Dependency Resolution. This subsystem acts as the primary dispatcher, directing requests to the appropriate business logic after ensuring all prerequisites (data parsing, validation, and dependency injection) are met.
This component is the primary interface for defining API endpoints. It maps incoming HTTP requests (based on method and path) to specific handler functions. It also allows for grouping routes, applying common prefixes, tags, and dependencies, thereby structuring the API.
Related Classes/Methods:
The core engine for FastAPI's dependency injection system. It analyzes the dependencies declared for a path operation (or other dependencies), recursively resolves them by extracting and validating data from the request, executing dependency callables, and then injecting the resolved values into the target function.
Related Classes/Methods:
This component provides a mechanism for developers to explicitly mark function parameters as dependencies. It acts as a signal to the Dependency Resolver, indicating that a specific callable (function or class) needs to be executed to provide the value for that parameter.
Related Classes/Methods:
A specialized type of dependency that encapsulates authentication and authorization logic. It's responsible for extracting security credentials (e.g., OAuth2 bearer tokens) from the request, validating them, and raising appropriate HTTP exceptions (e.g., 401 Unauthorized) if validation fails.
Related Classes/Methods: