Cannot add new collection in mongodb in mLab

I am following full-stack react course by stephen grider. Everything looks good but after google social auth, I can't see new users collection getting added to the mLab database.

I am using passport.js and mongoose.js.

Here is the relevant source code:

index.js

const express = require('express');
const mongoose = require('mongoose');
const keys = require('./config/keys');
require('./models/User');
require('./services/passport');

mongoose.connect(keys.mongoURI);

const app = express();

require('./routes/authRoutes')(app);

const PORT = process.env.PORT || 5000;
app.listen(PORT)

user.js

const mongoose = require('mongoose');
const { Schema } = mongoose;

const userSchema = new Schema({
  googleId: String
});

mongoose.model('users', userSchema);    

passport.js

const passport = require('passport');
const GoogleStrategy = require('passport-google-oauth20').Strategy;
const mongoose = require('mongoose');
const keys = require('../config/keys');

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

passport.use(
  new GoogleStrategy(
    {
      clientID: keys.googleClientID,
      clientSecret: keys.googleClientSecret,
      callbackURL: '/auth/google/callback'
    },
    (accessToken, refreshToken, profile, done) => {
      new User({ googleId: profile.id }).save();
      console.log('accessToken',accessToken,'profile',profile)
    }
  )
);

Could anyone please let me know where I am making mistake because of which new collection is not getting created in the MongoDB database?

The issue was in the user.js file. Defining Schema alone doesn't work. You will need to export it too.

const mongoose = require('mongoose');
const { Schema } = mongoose;

const userSchema = new Schema({
  googleId: String
});

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

Further, if anybody come across this type of error, please make sure you are using correct credentials(username and password) for the particular mongo database.