Rails is an amazing framework for Web Development. Most of us don`t really know how fast and easily you can create applications using Ruby on Rails. Rails applications has always had trouble with deployment (methods of deployment have improved with the latest versions) but nonetheless, the power of application development using Rails in least amount of time is something still other web frameworks cannot provide.

About this Article

Having said, this simple tutorial will not only teach you how to create your first application in Rails, but also information on how primitive generators are used in rails.

I am Assuming you have heard of Ruby on Rails and Model – View – Controller Architecture.

What are we building ?

A Simple application to add/edit/delete and view User Information. (Imagine it to be an Employee managing application). Our Primary goal is to create an application which will display all User info stored in the databse. It should allow us to

1. Create a New User
2. Edit an Existing User
3. Delete an Exisitng User
4. View All Users

There are many tutorials out there which explain how to create Rails applications, this article is intended for the newbies interested to know more about Ruby on Rails.

Index

1. Create Rails App
2. Configure Rails App to work with MySQL
3. Confirm connection with MySQL
4. Start Coding
5. Run Application
6. Add Validation to forms (to make it look prettier )
7. Conclusion

Requirements

Please note that, Rails 2.3.3 works best with Ruby 1.8.6 rather then Ruby 1.8.7 in a Windows powered local machine.

A system capable of running Ruby on Rails applications for development and testing purposes.

1. Create Rails App

   Open up “Command Prompt” (Start->Run (type in CMD ↵)). You can directly jump into creating your first Rails app by typing one of the following (remember we are creating a Rails app preconfigured to work with a MySQL Database)

   C:\myrailsapplications>rails myapp -d mysql↵
   OR
   C:\myrailsapplications>rails --database=mysql myapp↵

   

   Rails Application Structure

   
   

   Rails will create a host of directories with a similar structure as shown in the image.

   Now, if you want to create a MySQL based Rails application, use the above code to create one. Rails will create all the directories and configure your application to work with a MySQL Database instead of its default SQLite.

2. Configure your Rails app to work with MySQL

   Ok, we have created a Rails application to work with MySQL, but you need to specify the most important part for any application to connect to MySQL viz username, password.

   Navigate to myapp/config and open database.yml. We need to fill in the username and password for our MySQL Connection.

   Remember every Rails application can be run in any of the following 3 modes. Every mode has various pros and cons. We will be concentrating with the “development” mode.

   1. development
   2. production
   3. test

   This is how your database.yml should look like, with filled in values for username and password.

   
   development:
   adapter: mysql
   encoding: utf8
   reconnect: false
   database: myapp_development #will use this database for dev
   pool: 5
   username: root #my mysql username
   password: root #my mysql password
   host: localhost
   
   test:
   adapter: mysql
   encoding: utf8
   reconnect: false
   database: myapp_test
   pool: 5
   username: root #my mysql username
   password: root #my mysql password
   host: localhost
   
   production:
   adapter: mysql
   encoding: utf8
   reconnect: false
   database: myapp_production
   pool: 5
   username: root #my mysql username
   password: root #my mysql password
   host: localhost
   

3. Lets check the connection with MySQL.

   You know what the best part is…you have an option of either letting Rails do all the database manipulations directly, or you can use PHPMyAdmin or any other 3rd party tool. Rails is here to help us, from creating a database from scratch to modifyin it and till destroying it.

   Guess what, all of these actions are versioned (Rails likes to call this “migration”), so you can always go forth and back between various versions of your actions on manipulating the database

   Rails provides a Rake task that can take care of creating the database. Type the following commands to create teh databases directly via Rails.

   1. C:\myrailsapplications\myapp>  rake db:create RAILS_ENV='development'

      Yes Creates the database specified in the “development” section of database.yml

   2. C:\myrailsapplications\myapp>  rake db:migrate

      This is one of the most important commands in Rails. It is used everytime when you want to manipulate the database in any way. You`ll be seeing this command frequently being called everytime we have to manipulate teh database.

   Now its time to check whether our magic code worked or not. Either you’ll get the command prompt back (success) or you’ll get an error of some sort. The error means that Rails can’t currently work with your database. If you do see an error, It’s probably a simple configuration issue.

4. Lets start developing our User Managment Application

   What are we doing ?
   Our Primary goal is to create an application which will display all User info stored in the databse. It should allow us to

   1. Create a New User
   2. Edit an Existing User
   3. Delete an Exisitng User
   4. View All Users

   So we would require a table called “user” with attributes “firstname, lastname and salary”, to fetch the results from.

   Database Schema :

   

   User("id","firstname:string","lastname:string","salary:decimal")

   On an average, this application if done via PHP would take atleast anywhere between 0.5hours-1.5hrs (by a pro) and atleast 100-200 lines of code. Lets see what Rails has to offer.

   Start Coding :

   1. We`ll be using an unique generator in Rails to achieve this called Scaffold. This generator, automatically creates a model, controller and views of a particular object (in our case User)
      The Syntax to use a Saffold is
      C:\application directory> ruby script/generate scaffold A B
      A : Scaffold name (in our case “user”)
      B : what all attributes you want for this scaffold (What attributes do we need to store about a “user” viz “firstname,lastname and salary”Now that you know the syntax, lets run the code in the command prompt.

      Note : that on the command line that follows, we use the
      singular form, User instead of Users.

      In Rails, a model is automatically mapped to a database name mapping table whose name is the plural form of the model’s class. In our case, the model is called User, so Rails associated it with the table called users.

      C:\myrailsapplications\myapp>  ruby script/generate scaffold user fname:string lname:string salary:decimal
      

   2. You`ll notice a series of files being created after executing the above code. The one we’re interested in first is
      the migration 20090805075034_create_users.rb. The migration has a UTC based timestamp prefix (20090805075034), a name (create_users), and a file extension (.rb, because it’s a Ruby program).Since we already specified the columns we wanted to add on the command line, we don’t need to modify this file. All we need to do is to get Rails to apply this migration to our development database. We do this using the rake command.

      C:\myrailsapplications\myapp>  rake db:migrate

5. Run the Application

   Wondering why run the application without typing “actual” codes ? We must have typed barely 4 lines of code. Well thats the beauty of Rails.

   C:\myrailsapplications\myapp> ruby script/server

   

   Point your browser to http://localhost:3000/

   Now navigate your browser to http://localhost:3000/, You will see a page similar to the image in the left. You must be wondering what page is this ??

   Well this is Rails Welcome page, when you click on “About your Application’s Environment”, all the respective variables will be shown if your Rails application is successfully connected to the database else you will get an error.

   To see our application in action, navigate your browser to http://localhost:3000/users (since our scaffold was “user”)

   

6. Add Form Validation

   Navigate to “myapp/apps/models/” and open user.rb. Replace the code inside with

   
   class User < ActiveRecord::Base
   
   #checks for the presence of some text in firstname,lastname
   validates_presence_of :firstname, :lastname
   validates_numericality_of  :min_salary
   
   #call our function - min_salary
   validate :min_salary
   
   #function defination where salary is checked for its presence and minimum value
   def min_salary
   errors.add(:salary, 'should be at least 0.01' ) if salary.nil? ||
   salary < 0.01
   end
   
   end
   

   

   Our Validation Techniques seem to work

   Some Predefined Validation Checks
   validates_presence_of – Validates the presence of any character in that textfield
   validates_numericality_of – Validates the presence of any numerals in that textfield
   validates_uniqueness_of – Validates the uniqueness of that field (checks the database for the same name)
   
   

7. Conclusion

   I hope this tutorial is useful to all beginners learning Ruby on Rails. Rails 2.3.3 has introduced a lot of new features, and I`ll be covering as we go. If you guys have any questions, lemme know

About the Author

Michael is a freelance web developer. Fluent with PHP, Ruby on Rails, AJAX, CSS and HTML. Runs his own Web Designing Firm viz Vision Master Designs, who deal with customized solutions for business needs, blog design and development. Currently selected with this year's Google Summer of Code, working with Wordpres. Follow Michael on Twitter

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