Video demonstration of ruby on rails application creation:

One of the many advantages of rails is that it immediately gets you from zero to a functional application. To get started lets create a directory for the rails project called “railsproject”.

mkdir railsproject

Now open the ruby command prompt and navigate to the directory that we just created. Run the rails new command to make your first rails application. Let us call our first rails application as “first”. The rails new command is a program that creates a skeleton rails application. It creates a standard file and directory structure that makes it easier than ever to organize and deploy files. All the rails application have a common file and directory structure making it easy to understand someone else’s code.

rails new first

After the file creation is done rails automatically runs the bundle install command which we will discuss later in this article. Upon successful execution of the rails new command, it will display the message “Your bundle is complete!”

Output:

Bundle install command

Now lets have a quick look into the files and directories that have just been created. I use Aptana studio, an IDE for windows users of Rails.

Rails application directory structure

Let’s learn more about the files that have been created.

• app – This contains the Core application code including the models, views, controllers and helpers. The model, view and controller are very important parts of a rails architecture which we would learn in-depth in the later articles
• script/rails -A script to generate code and start the local server
• vendor – This contains third party code such as plugins and gems
• Gemfile – This file contains the gem requirements of the application

The bundle install or the bundler command which we had seen in the beginning of this article installs the gems from the Gemfile. The bundler looks for the gems that needs to be installed from this file. Thus the Gemfil should contain the gems needed by your application.

Gemfile:

source 'https://rubygems.org'
 
gem 'rails', '3.2.8'
 
# Bundle edge Rails instead:
# gem 'rails', :git => 'git://github.com/rails/rails.git'
 
gem 'sqlite3'
 
# Gems used only for assets and not required
# in production environments by default.
group :assets do
  gem 'sass-rails',   '~> 3.2.3'
  gem 'coffee-rails', '~> 3.2.1'
 
  # See https://github.com/sstephenson/execjs#readme for more supported runtimes
  # gem 'therubyracer', :platforms => :ruby
 
  gem 'uglifier', '>= 1.0.3'
end
 
gem 'jquery-rails'
 
# To use ActiveModel has_secure_password
# gem 'bcrypt-ruby', '~> 3.0.0'
 
# To use Jbuilder templates for JSON
# gem 'jbuilder'
 
# Use unicorn as the app server
# gem 'unicorn'
 
# Deploy with Capistrano
# gem 'capistrano'
 
# To use debugger
# gem 'debugger'

Inside the gemfile, the rails gem is the gem for rails itself. “sqlite3″ is the gem for the ruby interface to the SQLite database. ”jquery-rails”  is for the jQuery javascript library. As you could notice there is a version 3.2.8 specified in the rails gem command. Unless the version is explicitly specified, rails automatically deploys the latest version of that gem.