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

Question

hi, i'm writing a application under NodeJS but got the following 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 Object at Function.use (C:\Users\decopiapo\restserver1221\node_modules\express\lib\router\index.js:458:13) at Function. (C:\Users\decopiapo\restserver1221\node_modules\express\lib\application.js:220:21) at Array.forEach () at Function.use (C:\Users\decopiapo\restserver1221\node_modules\express\lib\application.js:217:7) at Server.routes (C:\Users\decopiapo\restserver1221\models\server.js:58:14) at new Server (C:\Users\decopiapo\restserver1221\models\server.js:19:14) at Object. (C:\Users\decopiapo\restserver1221\app.js:3:16) at Module._compile (node:internal/modules/cjs/loader:1101:14) at Object.Module._extensions..js (node:internal/modules/cjs/loader:1153:10) at Module.load (node:internal/modules/cjs/loader:981:32) [nodemon] app crashed - waiting for file changes before starting...

The Code is:

const {Router} = require('express');

const { check } = require('express-validator');

const { login} = require('../controllers/auth');

const { validatefields } = require('../middlewares/validate-fields');

const router = Router();

router.post('/login', [

check('email', 'Email is mandatory').isEmail(),

check('password', 'The Password is mandatory').not().isEmpty(),

validatefields

],

login);

module.exports = { router }

....

note

If i change "module.exports = { router }" for "module.exports = router" the problem disappears, but what if i want to export a constant or other function?

example:

const {Router} = require('express');

const { check } = require('express-validator');

const { login} = require('../controllers/auth');

const { validatefields } = require('../middlewares/validate-fields');

const myvar = '12321@as';

const router = Router();

router.post('/login', [

check('email', 'Email is mandatory').isEmail(),

check('password', 'The Password is mandatory').not().isEmpty(),

validatefields

],

login);

module.exports = { router, myvar }

the error appears again...

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

TypeError: Router.use() requires a middleware function but got a Object at Function.use

How i can solve this problem. Any Ideas?

Node Version: v16.11.1 - Express Version: 4.17.1

Answer 1

You can export is as you like, the problem is how you require it.

Check your server file, if you export it like this:

// router
module.exports = {myRouter, myvar};

then you need to require it like this:

// app
app.use('/', routerFile.myRouter);