implementing Dynamic Middleware Loading in Express.js Based on User Roles
I'm refactoring my project and I recently switched to I tried several approaches but none seem to work. I'm working with a scenario with dynamically loading middleware in my Express.js application based on user roles... I'm trying to ensure that only authorized users can access specific routes, but my implementation isn't working as expected. I've set up a basic Express server and I'm attempting to conditionally apply middleware depending on whether the user is an admin or a regular user. Here’s a simplified version of what I have: ```javascript const express = require('express'); const app = express(); const adminMiddleware = (req, res, next) => { if (req.user && req.user.role === 'admin') { next(); } else { return res.status(403).json({ message: 'Forbidden' }); } }; const userMiddleware = (req, res, next) => { if (req.user) { next(); } else { return res.status(401).json({ message: 'Unauthorized' }); } }; app.use((req, res, next) => { // Simulating user role assignment req.user = { role: 'user' }; // Change this to 'admin' to test admin access next(); }); app.get('/admin', adminMiddleware, (req, res) => { res.send('Welcome Admin'); }); app.get('/dashboard', userMiddleware, (req, res) => { res.send('Welcome User'); }); app.listen(3000, () => { console.log('Server running on port 3000'); }); ``` When I try to access the `/admin` route with the `req.user` role set to `'user'`, I get the expected `403 Forbidden` response, which is good. However, if I change the `req.user` role to `'admin'`, I get a `500 Internal Server behavior`, and the server logs show `TypeError: want to read properties of undefined (reading 'role')`. I’ve ensured that the middleware is applied in the correct order, and I can confirm that the user object is defined before the middleware runs. I’ve also checked that there are no other middleware that might be interfering. Interestingly, the `/dashboard` route works fine regardless of the user role changes. Is there something I'm overlooking in the route handling or middleware application that could lead to this scenario? Any insights or best practices on dynamic middleware loading would be greatly appreciated. Any ideas how to fix this? This issue appeared after updating to Javascript 3.10. Am I missing something obvious? I've been using Javascript for about a year now. Is this even possible?