/node-express-generator-08

#Express Generator

##What is it? Express generator, known to npm as express-generator, is something that will save you more time and typing than you can measure when starting an express back-end.

##Install it Like most node packages, we will be installing express-generator with npm.

Take note of the shell prompts. For Mac, you will be able to globally install this package with your ordinary account. For Linux, you will need superuser privileges. Prefix the command with sudo or otherwise assume a superuser (root) role before running it.

###Mac OS X

$ npm install -g express-generator

###Linux

# npm install -g express-generator

###Verify install Run this command to verify that express-generator has been successfully installed:

$ express -h

If successful, you should see this output:

Usage: express [options] [dir]

Options:

	-h, --help          output usage information
	-V, --version       output the version number
	-e, --ejs           add ejs engine support (defaults to jade)
		--hbs           add handlebars engine support
	-H, --hogan         add hogan.js engine support
	-c, --css <engine>  add stylesheet <engine> support (less|stylus|compass|sass) (defaults to plain css)
		--git           add .gitignore
	-f, --force         force on non-empty directory

##Use it For this lesson, we will be running express right in this repo's directory. We want it to use Handlebars for view rendering, since that's what we're familiar with, so we use the --hbs flag. Finally, we specify . for the directory to create files in. It will ask us to confirm since this is a non-empty directory.

$ express --hbs .

Now, having run that, take a look around at what express has generated for us:

$ ls -l

You should see a directory listing that resembles this:

-rw-rw-r-- 1 saad saad 1441 Aug 13 12:13 app.js
drwxr-xr-x 2 saad saad 4096 Aug 13 12:13 bin
-rw-rw-r-- 1 saad saad  339 Aug 13 12:13 package.json
drwxr-xr-x 5 saad saad 4096 Aug 13 12:13 public
-rw-rw-r-- 1 saad saad 1425 Aug 13 12:07 README.md
drwxr-xr-x 2 saad saad 4096 Aug 13 12:13 routes
drwxr-xr-x 2 saad saad 4096 Aug 13 12:13 views

##Files ###package.json This is the npm package file for your application. It contains various metadata, most importantly dependencies and development-only dependencies. Have a look at its contents by opening it up in Sublime or by running the following command:

$ less package.json

You should see something like this:

{
  "name": "node-express-generator",
  "version": "0.0.0",
  "private": true,
  "scripts": {
    "start": "node ./bin/www"
  },
  "dependencies": {
    "body-parser": "~1.13.2",
    "cookie-parser": "~1.3.5",
    "debug": "~2.2.0",
    "express": "~4.13.1",
    "hbs": "~3.1.0",
    "morgan": "~1.6.1",
    "serve-favicon": "~2.3.0"
  }
}

###app.js This file sets up and configues your app, the result of the express factory function (not to be confused with the command-line program). This is the core of our application. It wraps around an instance http.Server and provides a rich interface for us to build our back-end.

Since the goal of express, the web back-end framework, is to provide routing and act as the glue that holds your back-end together, this file will be the center of your application.

###routes/index.js In this file, we create and outfit a Router, then export it as a module. We consume the module in our app.js, mounting them on our app.

Creating Routers like this lets us organize our routes better. We can put all routes with the same prefix on the same router, then mount it on our app our another router.

###routes/*.js As above, these files serve to group our routes together. If you have a routes/users.js file, then you are expected to mount it on your app at path '/users'. routes/index.js is expected to be mounted on /.

###public/* This directory contains all your static assets. Things like CSS stylesheets, page scripts, and HTML pages belong here, each in their own subdirectory.

We won't be using this very much unless we use the serve-static middleware. In production, we'll rarely serve files from our express application, instead using a "true" web server to serve static content, since that is what they are frequently optimized for.

###views/* This is where your view templates go. This is only relevant for server-side templating, where we serve dynamically generated pages using templates and data available to our application, such as database rows or documents, from the server rather than serving JSON data and offloading the template rendering to the client-side.

Server-side templating is a valid approach, but is most useful in a limited subset of cases. One example is when rendering your templates requires data that you want to keep hidden from the client.

What sort of templates we have here will depend on the templating engine we chose when running the generator. The generator will give us some starter templates to start off with and embellish as we go.

###bin/www This is our start script. In fact, the express generator sets up npm start to run node ./bin/www. This script requires app.js, which exports app as a module, and uses app for what it was meant to do: be the callback for an instance of http.Server!

This is the file where we do startup-related things. If we want to sync our database models before listening for connections, this is where we write that code.

This is also one place where we can take care of out application's termination handlers. process is accessible anywhere, but this is the most appropriate place to set handlers for signals the process may or will receive that indicate that it is time to shut down. In these handlers, we can clean things up -- e.g., close database connections -- and call process.exit.

###models/* This is where your database models go. We'll gloss over this for now because we will have ample opportunity to discuss it as it comes up in following lessons.

###lib/* This is where we place our configuration and miscellaneous files. By having out configuration constants as modules, we make it easy for ourselves (and others) to modify them for special cases or deployment.

###log/* This is where you have your logging middleware write logs. Make sure to add this directory to your .gitignore!

##Run your application cd into the root directory of your application (the same one you ran the generator in) and run this command:

$ npm start