FastAPI Error Handling: Practical Guide to HTTP Status Codes and Exception Catching
API error handling is crucial for system robustness and user experience, and FastAPI provides a concise and efficient error handling mechanism. The core of the article includes: ### 1. Necessity of Error Handling It is necessary to clarify the error cause and use standard HTTP status codes (e.g., 404 for resource not found, 400 for parameter errors) to avoid system crashes and ensure service stability. ### 2. HTTP Status Codes and FastAPI Applications FastAPI supports all standard status codes. Route functions can directly specify them via `return` or `raise`. For example: `return {"detail": "Item not found"}` returns 404, or `HTTPException` can be used to explicitly throw errors. ### 3. FastAPI Exception Catching Mechanism It is recommended to actively throw errors using `HTTPException` with specified status codes and messages, such as returning 404 when a user does not exist. FastAPI automatically handles parameter type errors and returns a 422 status code. ### 4. Custom Exceptions and Global Fallback Business logic exceptions (e.g., insufficient balance) can be defined and uniformly handled using `@app.exception_handler` to return standard errors. The global exception handler falls back to uncaught exceptions to prevent server crashes. ### Best Practices Use `HTTPException` for standard errors, custom exceptions for business logic, and leverage automatic parameter
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This article introduces the method of building a web server using Node.js and Express. Based on the V8 engine, Node.js enables JavaScript to run on the server side, while Express, as a popular framework, simplifies complex tasks such as routing and request handling. For environment preparation, first install Node.js (including npm), and verify it using `node -v` and `npm -v`. Next, create a project folder, initialize it with `npm init -y`, and install the framework with `npm install express`. The core step is writing `server.js`: import Express, create an instance, define a port (e.g., 3000), use `app.get('/')` to define a GET request for the root path and return text, then start the server with `app.listen`. Access `http://localhost:3000` to test it. Extended features include adding more routes (e.g., `/about`), dynamic path parameters, returning JSON (`res.json()`), and hosting static files (`express.static`). The key steps are summarized as: installing tools, creating a project, writing routes, and starting the test, laying the foundation for subsequent learning of middleware, dynamic routing, etc.
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