node.js - Strange issue, model.find undefined in mongoose -

my model

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 connect mongodb via mongoose ...');  db.on('error', console.error.bind(console, 'mongoose connection error:')); db.once('open', function callback() {     console.log('connected mongodb !'); });  module.exports = {     user: require('../models/user.js')(mongoose), } 

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

when call save controller work fine when call throw exception in console same line db.user.find being called, log find method in console , print undefined. using mongoose version 4.0.1.