Strange issue, model.find undefined in mongoose

My model is

user.js

module.exports = function (mongoose) {

    var schema = new mongoose.Schema({
        name : String,
        emailAddress : String,
        lastActivity: { type: Date, default: Date.now },
        isActive : Boolean
    });

    return mongoose.model('User', schema);
}

db helper class db.js

var mongoose = require('mongoose');
mongoose.connect('mongodb://localhost/MyDatabase');
var db = mongoose.connection;

console.log('Try to connect to MongoDB via Mongoose ...');

db.on('error', console.error.bind(console, 'Mongoose connection error:'));
db.once('open', function callback() {
    console.log('Connected to MongoDB !');
});

module.exports = {
    User: require('../models/user.js')(mongoose),
}

And I use this in sails js controller

var db = require('../services/db.js');

module.exports = {
    save : function(req,res){
        var user = db.User({
            name: "govind",
            emailAddress: "govind@govind.com",
            isActive : true
        });
        user.save(function(){
            res.json({"response" : "successfully saved sample data"});
        });

    },
    get : function(req,res){
        console.log(db.User.find);    //this print undefined
        db.User.find(function (err, s) {
            res.json({"response" : s});
        });
    }
};

When I call save controller work fine but when I call get it throw exception in console same line where db.User.find is being called, I also log find method in console and this also print undefined. I am using mongoose version 4.0.1.