node.js - When I use mongoose & connect MongoDB, I can insert and get data. But unable to find data using MongoClient -

my code follows. open localhost/users/,brower return

{"_id":"55519446e063d4c409f93f00","username":"justnode","__v":0} 

but when open mongo shell , input: use student , db.student.find(),i can't find anything. mongodb version 3.0.1 , nodejs version 0.12.2, os centos 6.4

var express = require('express'); var bodyparser = require('body-parser'); var mongoose = require('mongoose'); var app = express();  mongoose.connect('mongodb://localhost/student', function (error) {     if (error) {         console.log(error);     } });  var schema = mongoose.schema;  var userschema = new schema({    username: {type: string, unique: true} });  var usermodel = mongoose.model('usermodel', userschema);  app.use(bodyparser.json()); app.use(bodyparser.urlencoded({ extended: false }));    /*   post content follows   {     "username": "justnode"   }  */ app.post('/users/create', function (req, res) {   console.log("in /users/create");   var usermodeljson = req.body;   var usermodel = new usermodel(usermodeljson);    usermodel.save(function(error) {     if(error) {       console.log(error);       return res.json({msg: "error"});     }     console.log("user created: " + usermodel.username);     res.json(usermodel);   }); }); /* open localhost/users/  brower return {"_id":"55519446e063d4c409f93f00","username":"justnode","__v":0}] when open mongo client: db.student.find()  can't find   */ app.get('/users', function (req, res) {   usermodel.find({}, function (err, docs) {       res.json(docs);   }); });  var serverapp = app.listen(80, function () {     console.log('express server listening on port ' + serverapp.address().port); }); 

change database(student), schema(userschema) , model(usermodel)'s name , try again. case, after changing variable's name , restart, works. (i've no idea why, maybe mongoose or mongo shell has bug?)