Getting Started with Ruby on Rails

by Erik Andrejko

Ruby on Rails is a popular framework for creating web applications and is especially suited for the rapid development of rich internet applications. Built on top of the object oriented language Ruby, Ruby on Rails includes a collection of tools and a template system for quickly building web applications. In many ways, Ruby on Rails is also a philosophy and you will find this influencing the way that web applications are built in Rails. As a framework, Ruby on Rails is organized in the Model-View-Controller (MVC) architecture. Integrated with Ruby on Rails are the popular Prototype and Scriptaculous JavaScript libraries that can be used to enhance a web application with AJAX.

Installation

Installation of Ruby on Rails requires installing Ruby and Ruby on Rails. Ruby may be installed on a variety of platforms and can be downloaded from: http://www.ruby- lang.org/en/downloads/. For installation on Windows, the best option is to install the “one-click installer”.

Ruby organizes its packages into ‘gems’ and the gem command is used to access the Ruby package management system. Once Ruby has been installed it is a good idea to update gem using the command:

gem update --system

Now that Ruby has been installed, the next step is to install Rails. Rails is distributed as a Ruby gem and can be installed just like any other gem. To install the Rails gem use the command:

gem install rails

The Rails gem will be installed with all of the necessary dependencies. On a Unix based system, like Linux or Mac OS X, it is often necessary to prefix all gem commands with the sudo command, as installing gems requires administrator rights. You will frequently see this pattern or prefixing the gem command with sudo mentioned online. In this case, the rails gem would be installed with:

	
sudo gem install rails

Creating a Ruby on Rails Application

Part of the philosophy of Rails includes using commands to generate code. The rails command is used to create a new Ruby on Rails project. To create the hello_world project use the command:

rails hello_world

This will create a Rails application directory structure in the hello_world subdirectory. Since Rails has a philosophy of convention over configuration every Rails application has the same directory structure and files in the same locations. The generated directory structure contains the following:

hello_world
|____app
| |____controllers
| |____helpers
| |____models
| |____views
|____config
|____db
|____doc
|____lib
|____log
|____public
| |____images
| |____javascripts
| |____stylesheets
|____script
|____test
|____tmp
|____vendor

As you can see, a new Rails project starts with a lot of structure. Some of the most important directories are:

• app: stores the models, controllers and views of the application
• public: this directory is used to store static HTML files, images, JavaScript and CSS files
• log: stores log files of all requests and errors
• script: contains utility functions to generate code to use in your application

Since Rails emphasizes convention over configuration, once you learn in which directories to find the various parts of an application, it will be the same for every Rails application that you encounter.

Getting Started with Ruby on Rails
Starting the Local Server