Error Login Mongoose and Bcrypt

I am having an issue trying to log using mongoose and bcrypt. I get the error:

TypeError: cb is not a function

My model:

const mongoose = require('mongoose');
const Schema =  mongoose.Schema;
const bcrypt = require('bcrypt');
SALT_WORK_FACTOR = 10;

const userSchema = Schema({
  email:{type: String, required: true},
  encrypted_password:{type: String},
  active:{type: Boolean},
  role_id:{ type: Schema.Types.ObjectId, ref: 'roles' ,required: true},
  create_date:{type: Date, default: Date.now},
});

userSchema.methods.comparePassword = function comparePassword(candidatePassword, cb) {
  bcrypt.compare(candidatePassword, this.password, function (err, isMatch) {
    if (err) {
      return cb(err);
    }

    cb(null, isMatch);
  });
};

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

My authentication method:

const express = require('express')
  , router = express.Router()
const app = express();
const jwt = require('jsonwebtoken');
app.set('superSecret', 'XXXXXXX');

Users = require('./../database/models/people_culture/user');

module.exports = function(app){

app.post('/api/authenticate', (req, res) => {
  Users.findOne({email: req.body.email}, function(err, user) {
    console.log(user)
    if (err) throw err;

    if (!user) {
      res.json({ success: false, message: 'Authentication failed. User not found.' });
    } else if (user) {
password.' });
      var ismatch = user.comparePassword(req.body.password);
      if(!ismatch){
        res.json({ success: false, message: 'Authentication failed. Wrong password.' });

      } else {

        var token = jwt.sign(user, app.get('superSecret'), {
          expiresIn: 1440 // expires in 24 hours
        });

        res.json({
          success: true,
          message: 'This is the key',
          token: token
        });
      }

    }

  });
});

app.use('/api', router);
}

I follow several tutorials and always get the same error. The function to hash the password works fine, but when I try to compare the password can't log in because of this error.

I am using Express, Mongoose, JsonWebToken and bcrypt to authenticate the user.

Thanks in advance

via joselegit