Getting Started with Ruby on Rails

Welcome,

Ruby on Rails is an extremely productive web application framework written in Ruby by David Heinemeier Hansson.

This is a open source Ruby framework for developing database-backed web applications.

To develop a web application using Ruby on Rails Framework, install the following software:

• Ruby
• The Rails framework
• A Web Server
• A Database System

We assume that you already have installed a Web Server and Database System on your computer. You can always use the WEBrick Web Server, which comes with Ruby. Most sites, however, use Apache or lightTPD in production.

Rails works with many database systems, including MySQL,PostgreSQL, SQLite, Oracle, DB2 and SQL Server. Please refer to a corresponding Database System Setup manual to setup your database.
Let's look at the installation instructions for Rails on Windows, Mac OS X, and Linux.

Rails Installation on Windows:

1. First, let's check to see if you already have Ruby installed. Bring up a command prompt and type ruby -v. If Ruby responds, and if it shows a version number at or above 1.8.2 then type gem --version. If you don't get an error, skip to step 3. Otherwise, we'll install a fresh Ruby.
2. If Ruby is not installed, then download an installation package from rubyinstaller.rubyforge.org. Follow thedownload link, and run the resulting installer. This is an exe like ruby186-25.exe and will be installed in a single click. You may as well install everything . It's a very small package, and you'll get RubyGems as well alongwith this package. 
3. With RubyGems loaded, you can install all of Rails and its dependencies through the command line:

C:\> gem install rails --include-dependencies

NOTE: Above command may take some time to install all dependencies. Make sure you are connected to the internet while installing gems dependencies.

Congratulations! You are now on Rails over Windows.

Rails Installation on Mac OS X:

1. First, let's check to see if you already have Ruby installed. Bring up a command prompt and type ruby -v. If Ruby responds, and if it shows a version number at or above 1.8.2 then skip to step 3. Otherwise, we'll install a fresh Ruby. To install a fresh copy of Ruby, the Unix instructions that follow should help.
2. Next you have to install RubyGems. Go to rubygems.rubyforge.org and follow the download link. OS X will typically unpack the archive file for you, so all you have to do is navigate to the downloaded directory and (in the Terminal application) type.

tp> tar xzf rubygems-x.y.z.tar.gz tp> cd rubygems-x.y.z rubygems-x.y.z> sudo ruby setup.rb

3. Now use RubyGems to install Rails. Still in the Terminal application, issue the following command.

tp> sudo gem install rails --include-dependencies

NOTE: Above command may take some time to install all dependencies. Make sure you are connected to the internet while installing gems dependencies.

Congratulations! You are now on Rails over Mac OS X.

Rails Installation on Linux:

1. First, let's check to see if you already have Ruby installed. Bring up a command prompt and type ruby -v. If Ruby responds, and if it shows a version number at or above 1.8.2 then skip to step 3. Otherwise, we'll install a fresh Ruby.
2. Download ruby-x.y.z.tar.gz from www.ruby-lang.org
3. Untar the distribution, and enter the top-level directory.
4. Do the usual open-source build as follows

tp> tar -xzf ruby-x.y.z.tar.gz tp> cd ruby-x.y.z ruby-x.y.z> ./configure ruby-x.y.z> make ruby-x.y.z> make test ruby-x.y.z> make install

5. Install RubyGems. Go to rubygems.rubyforge.org, and follow the download link. Once you have the file locally, enter the following in your shell window.

tp> tar -xzf rubygems-0.8.10.tar.gz tp> cd rubygems-0.8.10 rubygems-0.8.10> ruby setup.rb

6. Now use RubyGems to install Rails. Still in the shell, issue the following command.

tp> gem install rails --include-dependencies

NOTE: Above command may take some time to install all dependencies. Make sure you are connected to the internet while installing gems dependencies.

Congratulations! You are now on Rails over Linux.

Keeping Rails Up-to-Date:

Assuming you installed Rails using RubyGems, keeping up-to-date is relatively easy. Issue the following command:

tp> gem update rails

This will automatically update your Rails installation. The next time you restart your application it will pick up this latest version of Rails. While giving this command, make sure you are connected to the internet.

Installation Verification

You can verify if everything is setup according to your requirements or not. Use the following command to create a demo project.

tp> rails demo

This will generate a demo rail project, we will discuss about it later. Currently we have to check if environment is setup or not. Now next use the following command to run WEBrick web server on your machine.

tp> cd demo tp> ruby script/server => Rails application started on http://0.0.0.0:3000 => Ctrl-C to shutdown server; call with --help for options [2007-02-26 09:16:43] INFO WEBrick 1.3.1 [2007-02-26 09:16:43] INFO ruby 1.8.2 (2004-08-24)... [2007-02-26 09:16:43] INFO WEBrick::HTTPServer-start:pid=2836... ....

Now open your browser and type the following address text box.

http://localhost:3000

If everything is fine then you should have a message something like "Welcome aboard" or "Congratulations".

While you're developing Rails applications, especially those which are mainly providing you with a simple interface to data in a database, it can often be useful to use the scaffold method.

Scaffolding provides more than cheap demo thrills. Here are some benefits:

• You can quickly get code in front of your users for feedback.
• You are motivated by faster success.
• You can learn how Rails works by looking at generated code.
• You can use the scaffolding as a foundation to jumpstarts your development.

Scaffolding Example:

To understand scaffolding lets create a database called cookbook and a table called recipes:

Creating an Empty Rails Web Application:

Open a command window and navigate to where you want to create this cookbook web application. I used c:\ruby. So run the following command to create complete directory structure.

C:\ruby> rails cookbook

Setting up the Database:

Here is the way to create database:

mysql> create database cookbook; Query OK, 1 row affected (0.01 sec) mysql> grant all privileges on cookbook.* to 'root'@'localhost' identified by 'password'; Query OK, 0 rows affected (0.00 sec) mysql> FLUSH PRIVILEGES; Query OK, 0 rows affected (0.00 sec)

To tell Rails how to find the database, edit the configuration file c:\ruby\cookbook\config\database.yml and change the database name to cookbook. Leave the password empty. When you finish, it should look something like

development: adapter: mysql database: cookbook username: root password: [password] host: localhost test: adapter: mysql database: cookbook username: root password: [password] host: localhost production: adapter: mysql database: cookbook username: root password: [password] host: localhost

Rails lets you run in development mode, test mode, or production mode, using different databases. This application uses the same database for each.

Creating the database tables:

We will use following table for our practical purpose. So create recipes table from sql prompt as follows:

mysql> USE cookbook; Changed database mysql> CREATE TABLE recipes ( -> id INT(11) NOT NULL AUTO_INCREMENT, -> title VARCHAR(40), -> instructions VARCHAR(255), -> PRIMARY KEY (id)); Query OK, 0 rows affected (0.06 Sec)

NOTE: If you wish you can use Rails Migrations to create and maintain tables.

Creating Model:

First, create a Recipe model class that will hold data from the recipes table in the database. Use the following command inside cookbook directory.

C:\ruby\cookbook > ruby script\generate model Recipe

Notice that you are capitalizing Recipe and using the singular form. This is a Rails paradigm that you should follow each time you create a model.

This will create a file named app/models/recipe.rb containing a skeleton definition for the Recipe class.

Creating Controller:

Now we have to create a recipe controller with actions to manipulate the recipes in the database via the standard CRUD operations: create, read, update, and delete.

C:\ruby\cookbook > ruby script\generate controller Recipe

Notice that you are capitalizing Recipe and using the singular form. This is a Rails paradigm that you should follow each time you create a controller.

This will create a file named app/controllers/recipe_controller.rb containing a skeleton definition for the RecipeController class. Edit this file and add the line scaffold:recipe as shown

class RecipeController < ApplicationController scaffold:recipe end

This single line of code will bring the database table to life. This will provide with a simple interface to your data, and ways of:

• Creating new entries
• Editing current entries
• Viewing current entries
• Destroying current entries

When creating or editing an entry, scaffold will do all the hard work of form generation and handling for you, and will even provide clever form generation, supporting the following types of inputs:

• Simple text strings
• Textareas (or large blocks of text)
• Date selectors
• Datetime selectors

Now go into cookbook directory and run Web Server using following command:

C:\ruby\cookbook> ruby script/server

Now open a browser and navigate to http://127.0.0.1:3000/recipe/new, This will provide you a screen to create new entries in recipes table. A screen shot is shown below:




Once you press Create button to create anew recipe, your record is added into recipes table and it shows following result:







You can see option to edit, show and destroy the records. So play around these options.

You can also list down all the recipes available in the recipes table using URL http://127.0.0.1:3000/recipe/list