index.js

var express = require('express');
var mongoose = require ("mongoose"); // The reason for this demo.

// Here we find an appropriate database to connect to, defaulting to
// localhost if we don't find one.  
var uristring = 
  process.env.MONGODB_URI ||
  'mongodb://localhost,localhost:35046';

// The http server will listen to an appropriate port, or default to
// port 5000.
var theport = process.env.PORT || 5000;

// Makes connection asynchronously.  Mongoose will queue up database
// operations and release them when the connection is complete.
mongoose.connect(uristring, function (err, res) {
  if (err) { 
    console.log ('ERROR connecting to: ' + uristring + '. ' + err);
  } else {
    console.log ('Succeeded connected to: ' + uristring);
  }
});


var app = express();

app.set('port', (process.env.PORT || 5000));

app.use(express.static(__dirname + '/public'));

// views is directory for all template files
app.set('views', __dirname + '/views');
app.set('view engine', 'ejs');

app.get('/', function(request, response) {
  response.render('pages/index');
});

app.get('/db', function(request, response) {
  response.render('pages/db');
});

app.get('/about', function(request, response) {
  response.writeHead(200, {'Content-Type': 'text/html'});
  createWebpage(request, response);
});


// This is the schema.  Note the types, validation and trim
// statements.  They enforce useful constraints on the data.
var userSchema = new mongoose.Schema({
  name: {
    first: String,
    last: { type: String, trim: true }
  },
  age: { type: Number, min: 0}
});

// Compiles the schema into a model, opening (or creating, if
// nonexistent) the 'PowerUsers' collection in the MongoDB database
var PUser = mongoose.model('PowerUsers', userSchema);

// Clear out old data
PUser.remove({}, function(err) {
  if (err) {
    console.log ('error deleting old data.');
  }
});

// Creating one user.
var johndoe = new PUser ({
  name: { first: 'John', last: 'Doe' },
  age: 25
});

// Saving it to the database.  
johndoe.save(function (err) {if (err) console.log ('Error on save!')});

// Creating more users manually
var janedoe = new PUser ({
  name: { first: 'Jane', last: 'Doe' },
  age: 65
});
janedoe.save(function (err) {if (err) console.log ('Error on save!')});

// Creating more users manually
var alicesmith = new PUser ({
  name: { first: 'Alice', last: 'Smith' },
  age: 45
});
alicesmith.save(function (err) {if (err) console.log ('Error on save!')});

var alicesmith = new PUser ({
  name: { first: 'Prabhanshu', last: 'Attri' },
  age: 22
});
alicesmith.save(function (err) {if (err) console.log ('Error on save!')});


// In case the browser connects before the database is connected, the
// user will see this message.
var found = ['DB Connection not yet established.  Try again later.  Check the console output for error messages if this persists.'];

function createWebpage (request, response) {
  // Let's find all the documents
  PUser.find({}).exec(function(err, result) {
    if (!err) { 
      response.write(html1 + JSON.stringify(result, undefined, 2) +  html2 + result.length + html3);
      // Let's see if there are any senior citizens (older than 64) with the last name Doe using the query constructor
      var query = PUser.find({'name.last': 'Doe'}); // (ok in this example, it's all entries)
      query.where('age').gt(64);
      query.exec(function(err, result) {
		if (!err) {
		  response.write(html4 + JSON.stringify(result, undefined, 2) + html5 + result.length + html6);
		} else {
		  response.write('Error in second query. ' + err)
		}
	      });
    } else {
      response.write('Error in first query. ' + err)
    };
  });
}

// Tell the console we're getting ready.
// The listener in http.createServer should still be active after these messages are emitted.
console.log('http server will be listening on port %d', theport);
console.log('CTRL+C to exit');

//
// House keeping.

//
// The rudimentary HTML content in three pieces.
var html1 = '<title> hello-mongoose: MongoLab MongoDB Mongoose Node.js Demo on Heroku </title> \
<head> \
<style> body {color: #394a5f; font-family: sans-serif} </style> \
</head> \
<body> \
<h1> hello-mongoose: MongoLab MongoDB Mongoose Node.js Demo on Heroku </h1> \
See the <a href="https://devcenter.heroku.com/articles/nodejs-mongoose">supporting article on the Dev Center</a> to learn more about data modeling with Mongoose. \
<br\> \
<br\> \
<br\> <h2> All Documents in MonogoDB database </h2> <pre><code> ';
var html2 = '</code></pre> <br\> <i>';
var html3 = ' documents. </i> <br\> <br\>';
var html4 = '<h2> Queried (name.last = "Doe", age >64) Documents in MonogoDB database </h2> <pre><code> ';
var html5 = '</code></pre> <br\> <i>';
var html6 = ' documents. </i> <br\> <br\> \
<br\> <br\> <center><i> Demo code available at <a href="http://github.com/mongolab/hello-mongoose">github.com</a> </i></center>';





app.listen(app.get('port'), function() {
  console.log('Node app is running on port', app.get('port'));
});