Detailed Explanation of FastAPI Status Codes: Usage Scenarios for 200, 404, 500, etc.

HTTP status codes are numeric codes returned by servers to indicate the result of request processing. Proper configuration in FastAPI helps clients understand the outcome of requests. There are two ways to set status codes in FastAPI: directly returning a tuple (data + status code), or using the `HTTPException` exception (recommended for error scenarios). Common core status codes and scenarios: 200 (Request successful, used for returning data in GET/PUT, etc.); 404 (Resource not found, when GET/DELETE requests cannot locate the target); 500 (Internal server error, requires exception handling to avoid exposure); 201 (POST request successfully created a resource, returns the new resource); 204 (No content, successful DELETE/PUT with no returned data); 400 (Bad request, e.g., format or required field issues); 401 (Unauthorized, user not logged in); 403 (Forbidden, authenticated but with insufficient permissions). Best practices: Map status codes to corresponding HTTP methods, e.g., 200/404 for GET, 201 for POST, 204 for DELETE. Correctly using status codes prevents client-side errors, and FastAPI's Swagger documentation aids in debugging.