MongoDB与NodeJS连接错误

我目前正在尝试一个简单的Hello World应用程序使用MongoDB, Express, Swig和NodeJS

使用最新节点和其他依赖项。

Chrome 46.0(64位)。Mac OS X 10.9.5

var express = require('express'),
    app = express(),
    cons = require('consolidate'),
    MongoClient = require('mongodb').MongoClient,
    Server = require('mongodb').Server;
app.engine('html', cons.swig);
app.set('view engine', 'html');
app.set('views', __dirname + '/views');
var mongoclient = new MongoClient(new Server("localhost", 27017, {'native_parser':false}));
var db = mongoclient.db('course');
app.get('/', function(req, res){
    // Find one document in our collection
    db.collection('hello_mongo_express').findOne({}, function(err, doc) {
        if(err) throw err;
        res.render('hello', doc);
    });
});
app.get('*', function(req, res){
    res.send('Page Not Found', 404);
});
mongoclient.open(function(err, mongoclient) {
    if(err) throw err;
    app.listen(8080);
    console.log('Express server started on port 8080');
});

下面是我得到的错误当节点app.js:

AMAC02PC0PHG3QP:6_hello_world_express_swig_mongodb macadmin$ node app.js
Failed to load c++ bson extension, using pure JS version
/Users/macadmin/Desktop/NodeJS_MongoDB/6_hello_world_express_swig_mongodb/app.js:31
    if(err) throw err;
            ^
Error: failed to connect to [localhost:27017]
    at null.<anonymous> (/Users/macadmin/Desktop/NodeJS_MongoDB/6_hello_world_express_swig_mongodb/node_modules/mongodb/lib/mongodb/connection/server.js:553:25)
    at emitThree (events.js:97:13)
    at emit (events.js:175:7)
    at null.<anonymous> (/Users/macadmin/Desktop/NodeJS_MongoDB/6_hello_world_express_swig_mongodb/node_modules/mongodb/lib/mongodb/connection/connection_pool.js:140:15)
    at emitTwo (events.js:87:13)
    at emit (events.js:172:7)
    at Socket.<anonymous> (/Users/macadmin/Desktop/NodeJS_MongoDB/6_hello_world_express_swig_mongodb/node_modules/mongodb/lib/mongodb/connection/connection.js:512:10)
    at emitOne (events.js:77:13)
    at Socket.emit (events.js:169:7)
    at emitErrorNT (net.js:1250:8)

有些地方说写127.0.0.1而不是本地主机