/NodeJsCourseSummary

Notes of the course Learn and Understand NodeJS from Udemy. https://www.udemy.com/understand-nodejs/

1.Intro

Needs to make a web server

  • Better ways to organize our code into reusable pieces
  • Ways to deal with files
  • Ways to deal with databases
  • The ability to communicate over the Internet
  • The ability to accept requests and send responses
  • A way to deal with work that takes long time

2.Modules, Export and Require

Modules

Reusable block of code whose existence does not accidentally impact other code

Common JS Modules An agreed upon standard for how code modules should be structured

First class Functions Everything you can do with other types you can do with functions.
You can use functions like strings, numbers etc. ( i.e pass them around, set variables equal to them, put them in arrays and more )

Expression A block of code that results in a value

	// function statement
	function greet() {
		console.log('hi');
	}
	greet();

	// functions are first-class
	function logGreeting(fn) {
		fn();
	}
	logGreeting(greet);

	// function expression
	var greetMe = function() {
		console.log('Hi Tony!');
	}
	greetMe();

	// it's first-class
	logGreeting(greetMe);

	// use a function expression to create a function on the fly
	logGreeting(function() {
		console.log('Hello Tony!');
	});

Build a module

app.js

	var greet = require('./greet'); // returns what we have in `module.exports`
	greet();

greet.js

	var greet = function() {
		console.log('Hello!');
	};

	module.exports = greet;

Name value pair

A name which maps to a value. The name can be defined more than once, but only can have one value in any given context Address = "Sesam street"

Object

Collection of name/value pairs

Object Literal

Name/value pairs separated by commas and surrounded by curly braces

	var person = {
		name: 'Peter',
		lastname:'Doe',
		workplace:{
			Street:'Sesam street',
			Number: '1'
		},
		greet: function(){
				console.log('Hello ' + this.name + ' ' + this.lastname )
		}
	};

	person.greet();
	console.log(person['name'])

Prototypal inheritance

Every object points to a proto{} object

Function constructor

A function used to build objects using new

	function Person(firstname, lastname) {
		this.firstname = firstname;
		this.lastname = lastname;
	}


	Person.prototype.greet = function() {
		console.log('Hello, ' + this.firstname + ' ' + this.lastname);
	};

	var john = new Person('John', 'Doe');
	john.greet();

Immediately Invoked Functions Expressions (IIFEs)

Run the function at the point it is created. Add a () after its declaration.

	var firstname = 'Jane';

	(function (lastname) {

		var firstname = 'John';
		console.log(firstname);
		console.log(lastname);

	}('Doe'));

	console.log(firstname);

How Modules Work

require is a function, that you pass a 'path' to module.exports is what the require function returns this works because your code is actually wrapped in a function that is given these things as function parameters

app.js

	var greet = require('./greet'); // returns what we have in `module.exports`
	greet();

greet.js

	var greet = function() {
		console.log('Hello!');
	};

	module.exports = greet;

Require

app.js

	var greet = require('./greet');

	greet.english();
	greet.spanish();

greet/index.js

	var english = require('./english');
	var spanish = require('./spanish');

	module.exports = {
		english: english,
		spanish: spanish
	};

greet/english.js

	var greetings = require('./greetings.json');

	var greet = function() {
		console.log(greetings.en);
	}

	module.exports = greet;

greet/spanish.js

	var greetings = require('./greetings.json');

	var greet = function() {
		console.log(greetings.es);
	}

	module.exports = greet;

greet/greetings.json

	{
		"en": "Hello",
		"es": "Hola"
	}

Module Patterns

app.js

	var greet = require('./greet1');
	greet();

	var greet2 = require('./greet2').greet;
	greet2();

	var greet3 = require('./greet3');
	greet3.greet();
	greet3.greeting = 'Changed hello world!';

	var greet3b = require('./greet3');
	greet3b.greet(); // Returns 'Changed hello world!' -> The result of module.export is cached so the whole greet3 is only called once

	var Greet4 = require('./greet4');
	var grtr = new Greet4();
	grtr.greet();

	var greet5 = require('./greet5').greet;
	greet5();

greet1.js

	module.exports = function() {
		console.log('Hello world');
	};

greet2.js

	module.exports.greet = function() {
		console.log('Hello world!');
	};

greet3.js

	function Greetr() {
		this.greeting = 'Hello world!!';
		this.greet = function() {
			console.log(this.greeting);
		}
	}

	module.exports = new Greetr();

greet4.js

	function Greetr() {
		this.greeting = 'Hello world!!!';
		this.greet = function() {
			console.log(this.greeting);
		}
	}

	module.exports = Greetr;

greet5.js Revealing module pattern: Exposing only the properties and methods you want via a returned object

	var greeting = 'Hello world!!!!';

	function greet() {
		console.log(greeting);
	}

	module.exports = {
		greet: greet // Only the greet is "exposed" (public)
	}

Use always module.exports instead of export although they do the same.

Native Modules

nodejs.org/api

	var util = require('util');

	var name = 'Tony';
	var greeting = util.format('Hello, %s', name);
	util.log(greeting);

Modules and ES6

greet.js

	export function greet(){
		console.log('Hello');
	}

app.js

	import * as greetr from 'greet';
	greetr.greet();

3.Events And EventEmitter

Events

Something that has happened in our application that we can respond to

  • System Events: C++ core (libuv)
  • Custom Events: Javascript core (Event Emitter)

Object Properties and Methods

	var obj = {
		greet: 'Hello'
	}

	console.log(obj.greet);
	console.log(obj['greet']);
	var prop = 'greet';
	console.log(obj[prop]);

Functions and Arrays

	var arr = [];

	arr.push(function() {
		console.log('Hello world 1');
	});
	arr.push(function() {
		console.log('Hello world 2');
	});
	arr.push(function() {
		console.log('Hello world 3');
	});

	arr.forEach(function(item) {
		item();
	});

Node Event Emitter

Event Listener

The code that responds to an event

Our Event Emitter

Emitter.js

	function Emitter() {
		this.events = {};
	}

	Emitter.prototype.on = function(type, listener) {
		this.events[type] = this.events[type] || [];
		this.events[type].push(listener);
	}

	Emitter.prototype.emit = function(type) {
		if (this.events[type]) {
			this.events[type].forEach(function(listener) {
				listener();
			});
		}
	}

	module.exports = Emitter;

app.js

	var Emitter = require('./emitter');

	var emtr = new Emitter();

	emtr.on('greet', function() {
		console.log('Somewhere, someone said hello.');
	});

	emtr.on('greet', function() {
		console.log('A greeting occurred!');
	});

	console.log('Hello!');
	emtr.emit('greet');

Magic String

A String that has some special meaning in our code. Bad because of typos. Use config files instead.

	module.exports = {
		events: {
			GREET: 'greet'
		}
	}
	var Emitter = require('events');
	var eventConfig = require('./config').events;

	var emtr = new Emitter();

	emtr.on(eventConfig.GREET, function() {
		console.log('Somewhere, someone said hello.');
	});

	emtr.on(eventConfig.GREET, function() {
		console.log('A greeting occurred!');
	});

	console.log('Hello!');
	emtr.emit(eventConfig.GREET);

Prototype chain

Another way to create objects Object.create(...)

	var person = {
		firstname: '',
		lastname: '',
		greet: function() {
			return this.firstname + ' ' + this.lastname;
		}
	}

	var john = Object.create(person);
	john.firstname = 'John';
	john.lastname = 'Doe';

	var jane = Object.create(person);
	jane.firstname = 'Jane';
	jane.lastname = 'Doe';

	console.log(john.greet());
	console.log(jane.greet());

Inheriting from event emitter

Set to our object a prototype of the Emitter Allow us create objects with the Emitter properties

	var EventEmitter = require('events');
	var util = require('util');

	function Greetr() { // This is call to a "function constructor"
		this.greeting = 'Hello world!';
	}

	util.inherits(Greetr, EventEmitter); //<--

	Greetr.prototype.greet = function(data) {
		console.log(this.greeting + ': ' + data);
		this.emit('greet', data);
	}

	var greeter1 = new Greetr();

	greeter1.on('greet', function(data) {
		console.log('Someone greeted!: ' + data);
	});

	greeter1.greet('Tony');

ES5

Template literals

A way to concatenate strings in ES6

	var greet2 = `Hello ${ name }`;
	var a = 5;
	var b = 10;
	console.log(`Fifteen is ${a + b} and\nnot ${2 * a + b}.`);

call() and apply()

	var obj = {
		name: 'John Doe',
		greet: function() {
			console.log(`Hello ${ this.name }`);
		}
	}

	obj.greet();
	obj.greet.call({ name: 'Jane Doe'}); // this will point the what is passed in call
	obj.greet.apply({ name: 'Jane Doe'}); // idem

	// With params we see the difference
	var obj = {
		name: 'John Doe',
		greet: function(param1,param2) {
			console.log(`Hello ${ this.name }`);
		}
	}

	obj.greet.call({ name: 'Jane Doe'},param1,param2);
	obj.greet.apply({ name: 'Jane Doe'},[param1,param2]);

Inheriting pattern 2

We need the object that inherits to also have the this methods and properties of the inherited object.

	function Greetr() { // This is call to a "function constructor"
		EventEmitter.call(this) //<-- also called "super constructor"
		this.greeting = 'Hello world!';
	}
	var util = require('util');

	function Person() {
		this.firstname = 'John';
		this.lastname = 'Doe';
	}

	Person.prototype.greet = function() {
		console.log('Hello ' + this.firstname + ' ' + this.lastname);
	}

	function Policeman() {
		Person.call(this);// Without this line `this` object wont have firstname and lastname.
		this.badgenumber = '1234';
	}

	util.inherits(Policeman, Person);
	var officer = new Policeman();
	officer.greet();

ES6 Classes

	'use strict'; // like 'lint' for javascript

	class Person {
		constructor(firstname, lastname) {
			this.firstname = firstname;
			this.lastname = lastname;
		}

		greet() {
			console.log('Hello, ' + this.firstname + ' ' + this.lastname);
		}
	}

Inheriting in ES6 Classes

	var EventEmitter = require('events');

	class Greetr extends EventEmitter {
		constructor() {
			super();
			this.greeting = 'Hello world!';
		}

		greet(data) {
			console.log(`${ this.greeting }: ${ data }`);
			this.emit('greet', data);
		}
	}

4.Synchrony

Javascript is synchronous Node.js is asynchronous

libuv

A C library inside node that deal events occurring in the operating system

Buffer

Limited size, temporary place for data being moved from one place to another

Stream

A sequence of data made available over time

Binary data

Data store in binary

Character sets

A representation of characters as numbers (Unicode, Ascii...)

Encoding

How characters are stored in binary (UTF-8). Bits used to represent each number

Buffers

Needed because javascript was not used to deal with binary data. In ES6 it does using ArrayBuffer

	var buf = new Buffer('Hello', 'utf8');
	console.log(buf); //<Buffer 48 65 6c 6c 6f>
	console.log(buf.toString()); //Hello
	console.log(buf.toJSON()); // { type: 'Buffer', data: [ 72, 101, 108, 108, 111 ] }
	console.log(buf[2]); //108

	buf.write('wo');
	console.log(buf.toString()); // wollo

ArrayBuffer

ArrayBuffer Docs

	var buffer = new ArrayBuffer(8);
	var view = new Int32Array(buffer);
	view[0] = 5;
	view[1] = 15;
	console.log(view);	//Int32Array { '0': 5, '1': 15 }

Callbacks

	function greet(callback) {
		console.log('Hello!');
		var data = {
			name: 'John Doe'
		};

		callback(data);
	}

	greet(function(data) {
		console.log('The callback was invoked!');
		console.log(data);
	});

	greet(function(data) {
		console.log('A different callback was invoked!');
		console.log(data.name);
	});

	//Hello!
	//The callback was invoked!
	//{ name: 'John Doe' }
	//Hello!
	//A different callback was invoked!
	//John Doe

Files

	var fs = require('fs');

	//synchronous
	var greet = fs.readFileSync(__dirname + '/greet.txt', 'utf8');
	console.log(greet); //#1

	//asynchronous
	var greet2 = fs.readFile(__dirname + '/greet.txt', 'utf8', function(err, data) {
		console.log(data);//#3
	});

	console.log('Done!');//#2

Error First Callback

Callbacks take en error object as their first parameter. The Standard. null if no error.

Streams

Chunk

A piece of data being sent through a Stream Data is split in 'chunks' and streamed

	var fs = require('fs');

	var readable = fs.createReadStream(__dirname + '/greet.txt', { encoding: 'utf8', highWaterMark: 16 * 1024 }); // highWaterMark numebr of the buffer

	var writable = fs.createWriteStream(__dirname + '/greetcopy.txt');

	readable.on('data', function(chunk) { // Event emitter, just listenting the event starts the buffer
		console.log(chunk.length);
		// console.log(chunk);
		writable.write(chunk);
	});

Pipes

Conn ecting two streams by writing o one stream what is being read from another In node read from Readable stream to a Writable stream

	var fs = require('fs');
	var zlib = require('zlib');

	var readable = fs.createReadStream(__dirname + '/greet.txt');

	var writable = fs.createWriteStream(__dirname + '/greetcopy.txt');

	var compressed = fs.createWriteStream(__dirname + '/greet.txt.gz');

	var gzip = zlib.createGzip();

	readable.pipe(writable); // Same as forehead sample

	readable.pipe(gzip).pipe(compressed); // Chain pipes

Method chaining

A Method returns an object so we can keep calling more methods. When it returns the parent object is called "cascading".

5.HTTP

Protocol

A set of rules two sides agree on the use communicating. IP : Internet Protocol. Addresses TCP: Transmission Control Protocol. Send Packets

Port

Which program in a computer handles a packet received.

HTTP

A set of rules and format for data being transferred on the web 'Hypertext Transfer Protocol' (how the messages are written)

MIME Type

A standard for specifying the type of the data being sent 'Multipurpose Internet Mail Extensions' Examples: application/json, text/html, image/jpeg

http_parser

C program that parse http requests and responses

HTTP server

	var http = require('http');

	http.createServer(function (req, res) {

	  res.writeHead(200, {'Content-Type': 'text/plain'});
	  res.end('Hello World\n');

	}).listen(1337, '127.0.0.1');

Output HTML and Templates

	var http = require('http');
	var fs = require('fs');

	http.createServer(function(req, res) {

	    res.writeHead(200, { 'Content-Type': 'text/html' });
	    var html = fs.readFileSync(__dirname + '/index.htm', 'utf8');
	    var message = 'Hello world...';
	    html = html.replace('{Message}', message);
	    res.end(html);

	}).listen(1337, '127.0.0.1');

Template

Text designed to be the basis for final text or content after being processed

Streams and Performance

We can send chunks of data instead all at once using Streams and piping it to the response. Use it always.

	var http = require('http');
	var fs = require('fs');

	http.createServer(function(req, res) {

	    res.writeHead(200, { 'Content-Type': 'text/html' });
	    fs.createReadStream(__dirname + '/index.htm').pipe(res);

	}).listen(1337, '127.0.0.1');

API

Application Programing Interface. In node's field URLs which accept and send only data via HTTP and TCP/IP

Endpoint

One URL in a web API

Outputting a JSON

	var http = require('http');
	var fs = require('fs');

	http.createServer(function(req, res) {

	    res.writeHead(200, { 'Content-Type': 'application/json' });
	    var obj = {
	        firstname: 'John',
	        lastname: 'Doe'
	    };
	    res.end(JSON.stringify(obj));

	}).listen(1337, '127.0.0.1');

Serialize

Translating and object into a format that can be stored or transferred. JSON, CSV, XML are popular. 'Deserialize' is the opposite (converting the format back into an object)

Routing

Mapping HTTP requests to content. Get data in the server from parameters in the http call.

	var http = require('http');
	var fs = require('fs');

	http.createServer(function(req, res) {

	    if (req.url === '/') {
	        fs.createReadStream(__dirname + '/index.htm').pipe(res);
	    }

	    else if (req.url === '/api') {
	        res.writeHead(200, { 'Content-Type': 'application/json' });
	        var obj = {
	            firstname: 'John',
	            lastname: 'Doe'
	        };
	        res.end(JSON.stringify(obj));
	    }
	    else {
	        res.writeHead(404);
	        res.end();
	    }

	}).listen(1337, '127.0.0.1');

6.NPM

Semantic Versioning

MAYOR.MINOR.PATCH

Package.json

npm init npm install moment --save The --save writes a reference in package.json

	"dependencies": {
		"moment": "^2.13.0" // ^ automatically updates minors ~ updates only patches
	}

npm install : Once we have the package.json we dont need to copy the modules in a new environment, just calling npm install will download everything for us

require will look directly in the node_modules folder

	var moment = require('moment');
	console.log(moment().format("ddd, hA"));

Global dependencies

Install dependencies that we only need while developing npm install jasmine-node --save-dev Install globally, if we kwow we will us a package in many apps in our computer npm install nodemon -g They are stored at /usr/local/lib/node_modules/npm/node_modules

nodemon

It watches changes in the folder

7.Express

	var express = require('express');
	var app = express();

	var port = process.env.PORT || 3000;

	app.get('/', function(req, res) {
		res.send('<html><head></head><body><h1>Hello world!</h1></body></html>');
	});

	app.get('/api', function(req, res) {
		res.json({ firstname: 'John', lastname: 'Doe' });
	});

	app.listen(port);

Environment variables

Global variables specific to the environment (server) our code is living in.

Http method (verbs)

Specific type of action the request wishes to make. GET, POST, DELETE...

Routes

	app.get('/person/:id', function(req, res) {
		res.send('<html><head></head><body><h1>Person: ' + req.params.id + '</h1></body></html>');
	});

Static Files and Middleware

Midleware

Code that sit between 2 layers of software. In Express: sitting between request and response

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

	app.use('/', function (req, res, next) {
		console.log('Request Url:' + req.url);
		next(); // call the next Middleware
	});
	app.get('/', function(req, res) {
		res.send('<html><head><link href=assets/style.css type=text/css rel=stylesheet /></head><body><h1>Hello world!</h1></body></html>');
	});

Templates and Template Engines

	...

	app.set('view engine', 'ejs');

	app.get('/', function(req, res) {
		res.render('index');
	});

	app.get('/person/:id', function(req, res) {
		res.render('person', { ID: req.params.id });
	});
	...
	<html>
		<head>
			<link href="/assets/style.css" type="text/css" rel="stylesheet" /> // important the / before the path of the css
		</head>
		<body>
			<h1>Person: <%= ID %></h1>
		</body>
	</html>

Querystring and Post Parameters

Querystring

	GET /?id=4&page=3 HTTP/1.1
	Host:www.learnweb.net
	Cookie:username=abc:name:Tony
	app.get('/person/:id', function(req, res) {
		res.render('person', { ID: req.params.id, Qstr: req.query.qstr }); //req.query get the querystring
	});

Form Post

Data in the body as objects Use body-parser

	POST HTTP/1.1
	Host:www.learnweb.net
	Content-Type:application/x-www-form-urlencoded
	Cookie:num=4;page=3
	username=Tony&password=pwd
	var bodyParser = require('body-parser');
	var urlencodedParser = bodyParser.urlencoded({ extended: false });

	app.post('/person', urlencodedParser, function(req, res) {
		res.send('Thank you!');
		console.log(req.body.firstname);
		console.log(req.body.lastname);
	});
	<form method="POST" action="/person">
		First name: <input type="text" id="firstname" name="firstname" /><br />
		Last name: <input type="text" id="lastname" name="lastname" /><br />
		<input type="submit" value="Submit" />
	</form>

Post as json

Data in the body as json

	POST HTTP/1.1
	Host:www.learnweb.net
	Content-Type:application/json
	Cookie:num=4;page=3
	{
		'username'='Tony',
		'password'='pwd'
	}
	var jsonParser = bodyParser.json();

	app.post('/personjson', jsonParser, function(req, res) {
		res.send('Thank you for the JSON data!');
		console.log(req.body.firstname);
		console.log(req.body.lastname);
	});
	<script>
		$.ajax({
			type: "POST",
			url: "/personjson",
			data: JSON.stringify({ firstname: 'Jane', lastname: 'Doe' }),
			dataType: 'json',
			contentType: 'application/json'
		});
	</script>

RESTful API and JSON

REST

Representational State Transfer. Which HTTP verbs and URLs do what.

	app.get('/api/person/:id', function(req, res) {
		// get that data from database
		res.json({ firstname: 'John', lastname: 'Doe' });
	});

	app.post('/api/person', jsonParser, function(req, res) {
		// save to the database
	});

	app.delete('/api/person/:id', function(req, res) {
		// delete from the database
	});

Structuring the Application

Structuring with Express

install express-generator -g // do it global express <my app name>// Create the architecture cd <my app name> // go to the app npm install // install the packages

Our own Structure

Using controllers

app.js

	var express = require('express');
	var app = express();

	var apiController = require('./controllers/apiController');
	var htmlController = require('./controllers/htmlController');

	var port = process.env.PORT || 3000;

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

	app.set('view engine', 'ejs');

	app.use('/', function (req, res, next) {
		console.log('Request Url:' + req.url);
		next();
	});

	htmlController(app);
	apiController(app);

	app.listen(port);

htmlController

	var bodyParser = require('body-parser');

	var urlencodedParser = bodyParser.urlencoded({ extended: false });

	module.exports = function(app) {

		app.get('/', function(req, res) {
			res.render('index');
		});

		app.get('/person/:id', function(req, res) {
			res.render('person', { ID: req.params.id, Qstr: req.query.qstr });
		});

		app.post('/person', urlencodedParser, function(req, res) {
			res.send('Thank you!');
			console.log(req.body.firstname);
			console.log(req.body.lastname);
		});
	}

apiController

	module.exports = function(app) {

		app.get('/api/person/:id', function(req, res) {
		// get that data from database
			res.json({ firstname: 'John', lastname: 'Doe' });
		});

		app.post('/api/person', function(req, res) {
			// save to the database
		});

		app.delete('/api/person/:id', function(req, res) {
			// delete from the database
		});
	}

8.MEAN

DOM

Document Object Model The structure browsers use to store and manage web pages Browsers give JavaScript the ability to manipulate the DOM

Angular

app.js

	var express = require('express');
	var app = express();

	var port = process.env.PORT || 3000;

	app.set('view engine', 'ejs');
	app.use('/assets', express.static(__dirname + '/public'));

	app.get('/', function(req, res) {

		res.render('index');

	});

	app.listen(port);

view/index.ejs

	<html ng-app="TestApp">
		<head>
			<title>The MEAN stack</title>
	    	<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.5/angular.js"></script>
		</head>
		<body ng-controller="MainController as vm">

			<input type="text" ng-model="vm.message" />
			<br />
			{{ vm.message }}
			<br />
			<ul>
				<li ng-repeat="person in vm.people">
					{{ person.name }}
				</li>
			</ul>

			<script src="assets/js/app.js"></script>
		</body>
	</html>

public/js/app.js

	angular.module('TestApp', []);

	angular.module('TestApp')
		.controller('MainController', ctrlFunc);

	function ctrlFunc() {
		this.message = "Hello";

		this.people = [
			{
				name: 'John Doe'
			},
			{
				name: 'Jane Doe'
			},
			{
				name: 'Jim Doe'
			}
		]
	}

Separating Server code from Client code

We can set in the server what we show in client app.js

	var express = require('express');
	var app = express();

	var port = process.env.PORT || 3000;

	var people = [
		{
			name: 'John Doe'
		},
		{
			name: 'Jane Doe'
		},
		{
			name: 'Jim Doe'
		}
	];

	app.set('view engine', 'ejs');
	app.use('/assets', express.static(__dirname + '/public'));

	app.get('/', function(req, res) {

		res.render('index', { serverPeople: people }); //<--

	});

	app.listen(port);

view/index.ejs

	<html ng-app="TestApp">
		<head>
			<title>The MEAN stack</title>
			<script src="https://ajax.googleapis.com/ajax/libs/angularjs/1.4.7/angular.js"></script>
		</head>
		<body ng-controller="MainController as vm">
			<ul>
				<li ng-repeat="person in vm.people">
					{{ person.name }}
				</li>
			</ul>
			<script>
				var clientPeople = <%- JSON.stringify(serverPeople) %>; //<--
			</script>
			<script src="/assets/js/app.js"></script>
		</body>
	</html>

public/js/app.js

	angular.module('TestApp', []);

	angular.module('TestApp')
		.controller('MainController', ctrlFunc);

	function ctrlFunc() {
		this.people = clientPeople;
	}

9.Build an app

1. Init

*1 npm init *2 npm install express --save-dev *3 npm install ejs --save-dev *4 npm install body-parser --save-dev *5 npm install mongoose --save-dev

app.js

	var express = require('express');
	var app = express();

	var port = process.env.PORT || 3000;

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

	app.set('view engine', 'ejs');

	app.listen(port);

2. Connect to the Database

mLab.com config/config.json

	{
		"uname":"test",
		"pwd":"test"
	}

config/index.js

	var configValues = require('./config');

	module.exports = {
	    getDbConnectionString: function() {
	        return `mongodb://${configValues.uname}:${configValues.pwd}@ds013212.mlab.com:13212/nodetodo`;
	    }
	}

models/todoModel.js

	var mongoose = require('mongoose');

	var Schema = mongoose.Schema;

	var todoSchema = new Schema({
	    username: String,
	    todo: String,
	    isDone: Boolean,
	    hasAttachment: Boolean
	});

	var Todos = mongoose.model('Todos', todoSchema);

	module.exports = Todos;

app.js

	var express = require('express');
	var app = express();
	var mongoose = require('mongoose');
	var config = require('./config');

	var port = process.env.PORT || 3000;

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

	app.set('view engine', 'ejs');

	mongoose.connect(config.getDbConnectionString());

	app.listen(port);

3. Adding Data

controllers/setupController.js

	var Todos = require('../models/todoModel');

	module.exports = function(app) {

	   app.get('/api/setupTodos', function(req, res) {

	       // seed database
	       var starterTodos = [
	           {
	               username: 'test',
	               todo: 'Buy milk',
	               isDone: false,
	               hasAttachment: false
	           },
	           {
	               username: 'test',
	               todo: 'Feed dog',
	               isDone: false,
	               hasAttachment: false
	           },
	           {
	               username: 'test',
	               todo: 'Learn Node',
	               isDone: false,
	               hasAttachment: false
	           }
	       ];
	       Todos.create(starterTodos, function(err, results) {
	           res.send(results);
	       });
	   });

	}

app.js

	var express = require('express');
	var app = express();
	var mongoose = require('mongoose');
	var config = require('./config');
	var setupController = require('./controllers/setupController');

	var port = process.env.PORT || 3000;

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

	app.set('view engine', 'ejs');

	mongoose.connect(config.getDbConnectionString());
	setupController(app);

	app.listen(port);

Run http://localhost:3000/api/setupTodos

4. Create the API

controllers/apiController

	var Todos = require('../models/todoModel');
	var bodyParser = require('body-parser');

	module.exports = function(app) {

	    app.use(bodyParser.json()); // Middleware
	    app.use(bodyParser.urlencoded({ extended: true })); // Middleware

	    app.get('/api/todos/:uname', function(req, res) {

	        Todos.find({ username: req.params.uname }, function(err, todos) {
	            if (err) throw err;

	            res.send(todos);
	        });

	    });

	    app.get('/api/todo/:id', function(req, res) {

	       Todos.findById({ _id: req.params.id }, function(err, todo) {
	           if (err) throw err;

	           res.send(todo);
	       });

	    });

	    app.post('/api/todo', function(req, res) {

	        if (req.body.id) { // if i received an id I know that is an update
	            Todos.findByIdAndUpdate(req.body.id, { todo: req.body.todo, isDone: req.body.isDone, hasAttachment: req.body.hasAttachment }, function(err, todo) {
	                if (err) throw err;

	                res.send('Success');
	            });
	        }

	        else {

	           var newTodo = Todos({
	               username: 'test',
	               todo: req.body.todo,
	               isDone: req.body.isDone,
	               hasAttachment: req.body.hasAttachment
	           });
	           newTodo.save(function(err) {
	               if (err) throw err;
	               res.send('Success');
	           });

	        }

	    });

	    app.delete('/api/todo', function(req, res) {

	        Todos.findByIdAndRemove(req.body.id, function(err) {
	            if (err) throw err;
	            res.send('Success');
	        })

	    });

	}

app.js

	var express = require('express');
	var app = express();
	var mongoose = require('mongoose');
	var config = require('./config');
	var setupController = require('./controllers/setupController');
	var apiController = require('./controllers/apiController');

	var port = process.env.PORT || 3000;

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

	app.set('view engine', 'ejs');

	mongoose.connect(config.getDbConnectionString());
	setupController(app);
	apiController(app);

	app.listen(port);