Router.use() requires a middleware function but got a undefined

Question

I have this code in my index.js

... import userRoutes from './src/routes/userRoutes'; import invoicesRoutes from './src/routes/invoicesRoutes'; import authMiddleware from "./src/middlewares/authMiddleware"; ... const app = express(); ... app.use('/user', authMiddleware, userRoutes(app)); app.use('/invoices', authMiddleware, invoicesRoutes(app));

my authmiddleware

const authMiddleware = (req, res, next) => { if (req.headers && req.headers.authorization && req.headers.authorization.split(' ')[0] === 'JWT') { console.log(req.headers.authorization.split(' ')[0]); next(); } else { console.log('else'); next(); } }; export default authMiddleware;

and one of my routes:

import { register, login } from '../controllers/authController'; const userRoutes = (app) => { app.route('/user/signup') .post(register); app.route('/user/login') .post(login); }; export default userRoutes;

I'm getting an error:

throw new TypeError('Router.use() requires a middleware function but got a ' + gettype(fn)) ^

TypeError: Router.use() requires a middleware function but got a undefined

What's wrong?

Stamos · Accepted Answer · 2017-12-13 10:47:15Z

You pass your routes initialization as a middleware fuction app.use('/user', authMiddleware, userRoutes(app));

In this line of code what userRoutes(app) was supposed to return is function(req,res[,next]){}

Its should be like this

app.use('/user', authMiddleware, (req, res, next) => { userRoutes(app); next() })

and what you do is

app.use('/user', authMiddleware, (app) => { app.route('/user/signup').post(register); app.route('/user/login').post(login); })

that is wrong

There seems to be some bad logic here because from what I understand you will have to call http://localhost/user to initialize the routes and that will not work well beacuse of express's middleware inclusion.

Again from what I understand what you are trying to do should look more like this

... import userRoutes from './src/routes/userRoutes'; import invoicesRoutes from './src/routes/invoicesRoutes'; ... const app = express(); userRoutes(app); invoicesRoutes(app);

and

import { register, login } from '../controllers/authController'; import authMiddleware from "./middleware"; const userRoutes = (app) => { app.post('/user/signup', authMiddleware, register); app.post('/user/login', authMiddleware, login); }; export default userRoutes;

YouneL · Accepted Answer · 2017-12-13 12:05:17Z

Express already offer the Router class to separate routes in different sub-modules, So you can import userRoutes module without passing app variable into it, here is an example:

userRoutes.js

import { register, login } from '../controllers/authController'; import express from 'express'; const router = express.Router(); router.route('/signup') .post(register); router.route('/login') .post(login); export default router;

index.js

... import userRoutes from './src/routes/userRoutes'; import invoicesRoutes from './src/routes/invoicesRoutes'; import authMiddleware from "./src/middlewares/authMiddleware"; ... const app = express(); ... app.use('/user', authMiddleware, userRoutes); app.use('/invoices', authMiddleware, invoicesRoutes);

Hope this helps

lix · Accepted Answer · 2021-02-02 08:58:55Z

Check all your JavaScript files to make sure you are not missing this line:

module.exports = router

Tejasvi Manmatha · Accepted Answer · 2021-03-21 14:47:28Z

In my route.js

I had put it like this module.exports = routes;

what I intended to do was export routes, after changing it like below my error was gone module.exports = {routes};

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