TypeError: app.use() requires middleware functions

Question

This is my server.js file and api.js file. I am getting an error in the sort function in which I intend to search the js objects according to their attributes.The event Schema has the attributes as name, location, price, rating. I tried to sort it according to their prices.

server.js

var express= require('express'); var bodyParser= require('body-parser'); var morgan = require('morgan'); var config=require('./config'); var app= express(); var mongoose=require('mongoose'); //var User=require('./database/user') mongoose.connect('mongodb://localhost:27017/db',function(err){     if(err){         console.log(err);     }     else{         console.log("connected!");     } });  app.use(bodyParser.urlencoded({extended: true })); //if false then parse only strings app.use(bodyParser.json()); app.use(morgan('dev'));//log all the requests to the console var api=require('./app/routes/api')(app,express); app.use('/api',api); app.get('*',function(req,res){     res.sendFile(__dirname + '/public/views/index.html'); });   // * means any route  app.listen(config.port,function(err){     if(err){enter code here         console.log(err);     }     else{         console.log("The server is running");     } }); module.exports = router; 

api.js

var User = require('../models/user'); var Event = require('../models/event'); var config = require('../../config'); var secret = config.secretKey;  module.exports = function (app, express) {     var api = express.Router();     app.use()      api.post('/signup', function (req, res) {         var user = new User({             name: req.body.name,             username: req.body.username,             password: req.body.password         });         user.save(function (err) {             if (err) {                 res.send(err);                 return;             }             res.json({                 message: 'User created!'             });         });      });      api.get('/users', function (req, res) {         User.find({}, function (err, users) {             if (err) {                 res.send(err);                 return;             }             res.json(users);         });     });      api.post('/eventfeed', function (req, res) {         var event = new Event({             name: req.body.name,             location: req.body.location,             description: req.body.description,             price: req.body.price,             rating: req.body.rating         });          event.save(function (err) {             if (err) {                 res.send(err);                 return;             }             res.json({                 message: 'Event created!'             });         });     });      // utility function for sorting an array by a key in alpha order     api.get('/sortby_price', function (err) {         if (err) return err;             // utility function for sorting an array by a key in parsed numeric order         else {             function sortArrayNum(arr, key) {                 arr.sort(function (a, b) {                     return parseInt(a[key], 10) - parseInt(b[key], 10);                 });             }              var dicts = EventSchema.saved;             for (var i = 0; i < dicts.length; i++) {                 var terms = dicts[i].terms;                 sortArrayNum(terms, "price");             }         }         return api;     }); } 

This is my error. I am making a webpage for the first time using this. Kindly help me what does this error tells.

TypeError: app.use() requires middleware functions
at EventEmitter.use (c:\Users\MY APY\WebstormProjects\Main\node_modules\express\lib\application.js:209:11)
at module.exports (c:\Users\MY LAPY\WebstormProjects\Main\app\routes\api.js:10:9)
at Object. (c:\Users\MY LAPY\WebstormProjects\Main\server.js:20:36)
at Module._compile (module.js:460:26)
at Object.Module._extensions..js (module.js:478:10)
at Module.load (module.js:355:32)
at Function.Module._load (module.js:310:12)
at Function.Module.runMain (module.js:501:10)
at startup (node.js:129:16)
at node.js:814:3

Answer 1

I had this problem when I left out

module.exports = router; 

in my Routes.js.We need to export all the routes.

In my server.js, I had

var mainRoutes = require('./Routes.js') app.use(mainRoutes) 

So check your 'app/routes/api' file to see if it has proper export.