Practical Guide to FastAPI Middleware: Implementing Request Logging and Response Time Statistics
This article introduces the use of FastAPI middleware for uniformly handling request/response logic (such as logging and authentication) to avoid repetitive code. First, FastAPI and Uvicorn need to be installed. The core is to inherit Starlette's BaseHTTPMiddleware and implement the dispatch method to handle middleware logic: record the request start time, call call_next to obtain the response, calculate the response time, construct and output logs containing method, path, IP, response time, and status code. To add the middleware to the application, app.add_middleware must be called. During testing, define a simple route, access it, and the log will be output to the console. Extensions and optimizations can include using the logging module, recording request bodies, and exception handling. Middleware simplifies development, improves code maintainability, and is suitable for common logic such as authentication and CORS.
Read MoreFastAPI Middleware: How to Handle Cross-Origin, Authentication, and Other Request Interceptions
FastAPI middleware acts as a request/response interceptor, processing data before requests enter and responses return. Its core function is to uniformly handle requests and responses, with earlier-registered middleware executing first and executing in reverse order when returning. Typical applications include: 1. Cross-origin resource sharing (CORS): Implemented via CORSMiddleware, configuring allowed origins (e.g., "*" for development, specific domains for production), credentials, methods, and headers to resolve front-end cross-origin request issues. 2. Authentication interception: Custom middleware for global Token verification (e.g., Bearer Token), returning 401 for failed verification, distinct from dependencies (which target specific routes). Considerations include execution order, avoiding excessive interception, and distinguishing between middleware (for general logic) and dependencies (for local logic).
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