MEAN

Mongo, Express, Angular and Node.

Separation of Concerns

• Data Storage: Mongo
• HTTP Routing, Request, Response: Express
• Browser Front End: Angular
• Runtime: Node

Node.js

JavaScript, event-driven, non-blocking I/O.

const fs = require('fs');

fs.readFile('/path/to/file.txt', (err, data) => {
  if (err) return console.error('Error reading file', err);
  console.log('File contents', data);
});

Non-blocking I/O

console.log('Before');

fs.readFile('/path/to/file.txt', (err, data) => {
  console.log('In callback');
});

console.log('After');

// Output
> Before
> After
> In callback

CommonJS Module System

Node.js supports CommonJS modules through the builtin require() funciton.

const fs = require('fs');

To create a module, assign a value to module.exports. E.g.

// add.js
module.exports = (x,y) => {
  return x+y;
}

// myapp.js
const add = require('./add.js');
console.log(add(2, 3)); // => 5

NPM - Node Package Manager

• Package manager for Node.js
• Ships with Node
• ~300k packages

Express Quick Start

Assuming you already have Node.js and npm installed, install the express-generator package and create a new application.

$ npm install -g express-generator
$ express bookstore

This will create a skeleton framework for the bookstore application. Change into the application directory, install dependencies and start the app.

$ cd bookstore
$ npm install
$ DEBUG=bookstore:* npm start

Controller: Express Routing

The entry point to your application is index.js. Here the app is created, and routes are specified

const app = express();
app.get('/about', (req, res, next) => {
  res.send('<h1>Bookstore 1.0</h1>');
});

Routes can be modularized. In index.js

var routes = require('./routes/index');
var users = require('./routes/users');
// ...
app.use('/', routes);
app.use('/users', users);

Store your routes as modules in ./routes. Here is ./routes/index.js.

var express = require('express');
var router = express.Router();

/* GET home page. */
router.get('/', function(req, res, next) {
  res.render('index', { title: 'Express' });
});

module.exports = router;

View: Server side templates

The app.render function used in our index.js looks in a static view directory that has been configured on the app. Templating is specified with 'view engine'.

// view engine setup
app.set('views', path.join(__dirname, 'views'));
app.set('view engine', 'jade');

Templating with Jade

Express provides a several templating engines. Jade is the default. Here is a basic layout generated in ./views/layout.jade.

doctype html
html
  head
    title= title
    link(rel='stylesheet', href='/stylesheets/style.css')
  body
    block content

Angular Front End

• Insert some content here - PH todo

Model: MongoDB

• Document based storage
• JSON is lingua franca
• Natural fit with JavaScript

Install the mongodb module and save to your package.json.

$ npm install --save mongodb

Mongo Example

Obtain a MongoClient, and connect to the mongo server. To get a listing of all books of fiction in our hypothetical data store, let's create a function.

function getFiction(cb) {
  var MongoClient = require('mongodb').MongoClient;
  MongoClient.connect('mongodb://localhost:27017/books', function(err, db) {
    if (err) {
      return cb(err);
    }
    db.collection('fiction').find().toArray(function(err, result) {
      if (err) {
        return cb(err);
      }
      cb(null, result);
    });
  });
}

Now we can use this in a route.