connectivity to mongodb issue - node.js

Question

I have the following code in a script.js file:
var express = require('express'),
app = express(),
cons = require('consolidate'),
MongoCl = 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 MongoCl( new Server('localhost', 27017, {'native_parser' : true}));
var db = mongoclient.db('course');
app.get('/', function (req,res) {
db.collection('hello_mongo_express').findOne({}, function (err, doc) {
res.render('hello',doc);
});
});
app.get('*', function (req,res) {
res.send('Page not found',404);
});
mongoclient.open(function (err, mongoclient) {
if(err) throw err;
var port = 8080;
app.listen(port);
console.log("Express server started on port "+port);
});
./views/hello.html looks like :
<h1>Hello, {{name}}</h1>
I have a valid collection within a db 'course'.
When I try running using node, I face the following issue:
F:\mongo_proj>node script.js
F:\mongo_proj\script.js:11
var db = mongoclient.db('course');
^
TypeError: mongoclient.db is not a function
at Object.<anonymous> (F:\mongo_proj\script.js:11:22)
at Module._compile (module.js:409:26)
at Object.Module._extensions..js (module.js:416:10)
at Module.load (module.js:343:32)
at Function.Module._load (module.js:300:12)
at Function.Module.runMain (module.js:441:10)
at startup (node.js:139:18)
at node.js:968:3
Even though, I guess all the code that creates the mongoclient, db objects, will get called only when the db connectivity is been established. So what could the issue be
edit:
I tried #jerry's suggestion:

Answer 1

try this.. this simple way of connection
var MongoClient = require('mongodb').MongoClient
, assert = require('assert');
// Connection URL
var url = 'mongodb://localhost:27017/myproject';
// Use connect method to connect to the Server
MongoClient.connect(url, function(err, db) {
assert.equal(null, err);
console.log("Connected correctly to server");
db.close();
});
refer this link and try this
https://www.npmjs.com/package/mongodb

Answer 2

This issue is coming because, you are trying to use mongoclient before it opens connection. So wrap the code in open function as follow:
var db;
mongoclient.open(function (err, mongoclient) {
db = mongoclient.db('course');
if(err) throw err;
var port = 8080;
app.listen(port);
console.log("Express server started on port "+port);
});
See the link for further reference mongo connection
Also this .open() method is used in older versions. With newer version use .connect() method instead. For later versions may be refer this node driver manual