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.