Choosing an IDE or Editor

I have downloaded the RubyMine from Jetbrains who are the makers of famous ReSharper for .NET guys and IntelliJ for Java. I generally like the products of Jetbrains but I see RubyMine is still in its early stages and not free. You may still download the product and try it for 30 days.

Frankly, I see RubyMine tries to do a lot, download bundles run rails, use any rails generators but since we are in the learning stages and understanding under the hood, it is better to go with a basic normal editor.

The editor I am going to use is BlueFish which I mentioned before. BlueFish is a very nice simple editor which makes it easy to browse folders, create files, and also nice syntax highlighting for different languages ( html , javascript , java , ruby , PHP, PERL , Python )

Folder tree is refreshed automatically if you click one time to the folder ( wow! ) It is very handy if you use rails through command line!

New Rails project

Lets start with writing code. First of all we need to create a new rails application. In order to do that open up a console and run the following command

creates a new demo1 project. The project is empty which means there are no mappers, controllers or views are created for you. New command only generates a basic Rails project structure.

Mapper

config/routes.rb here you define a new route for the request handling

• open up the config/routes.rb
• Go to line 51
• root :to => "home#index"
• uncomment the root and change the string with home#index

Basically with this piece of code we tell rack that we will have a home controller and in that home controller there will be method called index. Lets create that controller first

• go to app/controllers
• add a new file called home_controller.rb
• in that file place the following line of code

class HomeController < ApplicationController
   def index
     @message = " Hello from the home controller"
   end
end

We don’t want to place any html inside the controller, so let’s create our view as well. The file extension of the html file will be .erb which stands for eRuby that is the ruby templating file like asp or jsp

• go to app/views/
• create a folder called home
• create a file named index.html.erb
• and place the following code.

<h1>
	<%=@message%>
</h1>

It is important to understand that all the files and code placed inside is a convention.

• home_controller.rb maps with root :to => "home#index"
• and the class
• HomeController maps with root :to => "home#index"
• def index maps with root :to => "home#index" and index.html.erb as well

To try how things will be broken, just rename one of the following into “homex” and see the errors.

Using Query Strings

Make a request to your home http://localhost:3000/?m=testtest Rails contains an object called params and to get the value of the m query string

@user_messsage = params [ :m ] 

Open your index.html.erb to modify the html and print out the parameter that passed in ( which is a bad idea to directly output the value )

 <h1> <%=@message%> & <%=@user_message%>  </h1>

and if you refresh you browser you will see

Hello from the home controller & testtest

but if you pass in an html tag with your query string , Rails 3 will automatically encode the output http://localhost:3000/?m=testtest<h2>

Forms

Create a form and post the information to server and back Create a new file called new.index.erb under your views/home folder paste the following code ( normal way, not rails way! )

<form action="/home/create" action="post">
  <input name="message" />
  <input type="submit" value="submit" />
</form>

and we need to map this action in our routes file.

• Open up config/routes.rb
• Add the following line under root ( line 51 )
• match "home/new" => "home#new"
• means that when you receive a request to home/new call the home controller’s new action.
• Lets define our action in home_controller.rb

  def new
  end
  				

• fire up the browser and navigate to http://localhost:3000/home/new
• you should see a simple textbox with a submit button and when you press the button, you will get an error says that

Routing Error
No route matches "/home/create"

Routing

Rather than mapping all the actions one by one, we may remove ( comment ) the match line and active the line 57

match ':controller(/:action(/:id(.:format)))'

which will do the auto mapping for us. ( sounds familiar with ASP.NET MVC global.asax routing definitions ? :)

We previously define basic html to post our data to the server, but in rails you don’t need to write that piece of code.

<% form_tag ( 'create' ) do %>
	<input name="message" />
	<input type="submit" value="submit" />
<% end %>

navigate to http://localhost:3000/home/new

def create
  	@message = params[:message]
  	# new in Rails 3 build in, use notice
	redirect_to "/" , :notice => @message
  end

and refactor index.html.erb into

<h1>
	<%=@message%>
</h1>
<%=notice%>

as you realized, we did not use the @user_message but use the notice session parameter which we set in the create method

CRUD

So far we went with the basics but the real power of rails starts with database operations and how easy to manage, generate and iterate. We start with the rails generator Scaffold

This will tell the rails that, hey rails 

• I want have a new model called pint
• Pint will have two fields which are
• Name is a string
• Price is a decimal field

Rails does not like singular form of models ( like pint in this scenario ) Here is the output rails 3 generates

bahadir@ubox:~/RubymineProjects/demo1$ rails g scaffold pint  name:string price:decimal
      invoke  active_record
      create    db/migrate/20110206113538_create_pints.rb
      create    app/models/pint.rb
      invoke    test_unit
      create      test/unit/pint_test.rb
      create      test/fixtures/pints.yml
       route  resources :pints
      invoke  scaffold_controller
      create    app/controllers/pints_controller.rb
      invoke    erb
      create      app/views/pints
      create      app/views/pints/index.html.erb
      create      app/views/pints/edit.html.erb
      create      app/views/pints/show.html.erb
      create      app/views/pints/new.html.erb
      create      app/views/pints/_form.html.erb
      invoke    test_unit
      create      test/functional/pints_controller_test.rb
      invoke    helper
      create      app/helpers/pints_helper.rb
      invoke      test_unit
      create        test/unit/helpers/pints_helper_test.rb
      invoke  stylesheets
      create    public/stylesheets/scaffold.css

After that check out the folders in your folder structure. Let’s migrate the database so that our model is also reflected ( huh did we have already a database setup ? :) Well, Sqlite is already in place and rails already made the setup for us.

bahadir@ubox:~/RubymineProjects/demo1$ rake db:migrate
(in /home/bahadir/RubymineProjects/demo1)
==  CreatePints: migrating ====================================================
-- create_table(:pints)
   -> 0.0018s
==  CreatePints: migrated (0.0019s) ===========================================

• navigate to http://localhost:3000/pints
• add couple of records now let’s do some trick
• Open up pints_controller.rb
• and the following 2 lines

  format.xml  { render :xml => @pints } after this.
  format.json { render :json=>@pints}
  format.text { render :text=>@pints}
  

• and navigate to
• http://localhost:3000/pints.json or http://localhost:3000/pints.text or http://localhost:3000/pints.xml

I am amazed how easy it is! Hold on a second, we did not setup any routing and application responds us. How could it be happen ? Open up routes.rb file Line 2 is added by the rails generator