Handling Route Parameters in Express for Dynamic API Endpoints with Validation
I'm upgrading from an older version and Hey everyone, I'm running into an issue that's driving me crazy... I tried several approaches but none seem to work. Currently developing a REST API using Express.js, and I'm trying to manage route parameters effectively. My API needs to handle dynamic endpoints like `/users/:id` where `id` is a user ID that needs to be validated against certain criteria (e.g., it should be a positive integer). I’ve created middleware for validation, but I'm unsure if I’m implementing it correctly. The middleware seems to run, but sometimes the API returns a 500 error instead of the expected 400 for invalid IDs. Here’s what I have: ```javascript const express = require('express'); const app = express(); // Middleware to validate user ID function validateUserId(req, res, next) { const userId = parseInt(req.params.id, 10); if (!Number.isInteger(userId) || userId <= 0) { return res.status(400).json({ error: 'Invalid user ID' }); } next(); } app.get('/users/:id', validateUserId, (req, res) => { // Simulate fetching user const user = { id: req.params.id, name: 'John Doe' }; // Assume we found the user res.json(user); }); app.listen(3000, () => { console.log('Server is running on port 3000'); }); ``` I've tested the validation independently, and it seems to fail when I send a string instead of an integer. However, instead of throwing a 400 error as expected, I sometimes get a 500 error in certain cases. What am I missing here? Should I also be catching any exceptions thrown during the fetching process to return a more graceful response? Additionally, are there better practices for validating route parameters in Express that I should consider? Any insights would be greatly appreciated! For context: I'm using Javascript on Linux. What am I doing wrong? Could this be a known issue?