类型错误：用户不是构造函数

Question

I am trying to save a user to mongodb database using post request as follow, but I got the error TypeError: User is not a function. It's a pretty simple set up of the code but i can't figure out anything wrong with it.

I am using:
mongoose 4.8.6
express 4.15.2
node 6.6

// models/user.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
    email: {
        type: String,
        unique: true,
        lowercase: true
    },
    password: String
});

// server.js
var User = require('./models/user');

app.post('/create-user', function(req, res, next) {
    var user = new User(); // TypeError: User is not a constructor
    user.email = req.body.email;
    user.password = req.body.password;

    user.save(function(err) {
        if (err) return next(err);
        res.json('Successfully register a new user');
    });
});

Answer 1

You need to create model from your UserSchema and then export it, then you can create new User objects.

// models/user.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;

var UserSchema = new Schema({
    email: {
        type: String,
        unique: true,
        lowercase: true
    },
    password: String
});

module.exports =  mongoose.model('User', UserSchema)

Answer 2

// models/user.js
var mongoose = require('mongoose');
var Schema = mongoose.Schema;
var UserSchema = new Schema({
    email: {
        type: String,
        unique: true,
        lowercase: true
},
    password: String
});

var User = mongoose.model('User', UserSchema)
module.exports =  { User } <-- capital 'U'

Answer 3

Changing the lowercase user variable into uppercase (like below) strangely worked:

const User = mongoose.model('users');

I really thought this was just a best practice but eventually, seems to be mandatory.

Answer 4

You got that error because you exported the modules wrongly,
In my case in the models/user I had written module.export leaving out the s at the end
When you run the code it then gives you that error
I would advice checking on your module.exports = mongoose.model('User', UserSchema) spellings

Answer 5

Change this var user = new User(); for this var User = new User();

Answer 6

I was also facing the same error but this worked for me.

I did change my export file

var User = mongoose.model('User',userSchema);
module.exports = {User};

To

module.exports = mongoose.model('User', userSchema);