throw new TypeError('Router.use() 需要中间件函数，但得到了一个 ' + gettype(fn));

Question

I have created an express application with MongoJS. I am returning a function, still it's showing an object has been returned. I have even added module.exports=router in my JavaScript page. Can someone please point out the missing export here?

app.js :

var express = require('express');
var define = require('./user/userSlots');
var app = express();
app.set("views", "./view");
app.use('/', define);
app.listen(3111, function () {
    console.log('Example app listening on port 3111!');
});

userSlots.js :

var express = require('express');
var module = require('../admin/dbModule');
var router = express.Router();

router.get('/login', function(request, response) {
    var username = request.params.username;
    var email = request.params.email;
    module.authenticateUser(username, email, response);
});
module.exports = router;

dbModule.js :

var mongojs = require("../../node_modules/mongojs");
var databaseUrl = "localhost/user";
var db = mongojs(databaseUrl);
var test = db.collection('user_information');
var message = null;
db.user_information.ensureIndex({ email: 1 }, { unique: true });
exports.authenticateUser = function(username, email, response) {
    db.user_information.find({ username: username, email: email }, function(err, users) {
        if (err || !users) {
            console.log("Failure");
            message = "Failure";
            reponse.render('index', { title: 'Hello', message: message });
        } else if (users.length == 0) {
            console.log("Not Valid user");
            message = "Failure";
            reponse.render('index', { title: 'Hello', message: message });
        } else {
            console.log("valid");
            message = "Success";
            reponse.render('index', { title: 'Hello', message: message });
        }
    });
}

Error:

E:\Vehicles\vehicles.com\node_modules\express\lib\router\index.js:458

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

TypeError: Router.use() requires middleware function but got a Object
    at Function.use (E:\Vehicles\vehicles.com\node_modules\express\li
b\router\index.js:458:13)
    at EventEmitter.<anonymous> (E:\Vehicles\vehicles.com\node_module
s\express\lib\application.js:220:21)
    at Array.forEach (native)
    at EventEmitter.use (E:\Vehicles\vehicles.com\node_modules\expres
s\lib\application.js:217:7)
    at Object.<anonymous> (E:\Vehicles\vehicles.com\application\app.j
s:12:5)
    at Module._compile (module.js:570:32)
    at Object.Module._extensions..js (module.js:579:10)
    at Module.load (module.js:487:32)
    at tryModuleLoad (module.js:446:12)
    at Function.Module._load (module.js:438:3)

Answer 1

You are causing a problem by redefining module in this line:

var module = require('../admin/dbModule');

And, then expecting it to be the original, built-in module later with this:

module.exports = router;

Change this:

var module = require('../admin/dbModule');

to a different name:

var dbModule = require('../admin/dbModule');

And, then use dbModule to refer to your database module and then the built-in module will still be available for normal use in module.exports .