奇怪的问题，model.find未定义在mongoose中

Question

我的模特是

  

user.js的

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),
}

我在sails js controller中使用它

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});
        });
    }
};

当我调用save controller工作正常但是当我调用get它在调用db.User.find的控制台同一行中抛出异常时，我也在控制台中记录find方法，这也打印undefined。我正在使用mongoose版本4.0.1。