Carlos Matallín

The Rails Way

These days I am trying to accomplish one of my 2009 New Year’s resolutions: Learn Ruby on Rails and be able to prototype, code and design one functional web application (you know, I’m in exams time…)

I have already worked with Ruby on Rails before, but only from the designer’s point of view: being able to implement my designs without the application to crash. Anyway the workflow with RoR, the philosophy behind and its singularities definitely definitely hooked me. Furthermore I must say to my own shame that I have only coded in C programming language in order to pass my practical lessons at the University.

To gain an insight into what I am talking about let’s face a real problem with which I had to deal while I am building this application.

Users must be able to register in the application, that will create a visit card for them with their data. One of the RoR conventions is the MVC architecture pattern that ensures the DRYness of your code (that’s a bunch of acronyms!). This is the piece of code from the Controller that was in charge of that (I am taking for granted some knowledge about these terms; if not, go Google them as I did before because they are really easy to understand):
/app/controllers/users_controller.rb

class UsersController < ApplicationController
  def create
    @user = User.new(params[:user])
    @card = Card.new
    @card.user_id = @user.id
    @card.title = "Visit card of #{@user.login}"
    if @user.save && @card.save
      flash[:notice] = "Account registered!"
      redirect_back_or_default account_url
    else
      render :action => :new
    end
  end
end

In RoR, there are always some mantras that one must follow in order to program good pieces of code, this way we will end up with an application that has everything in its right place and works properly. One of these mantras is Skinny Controller Fat Model, which says that many of our business logic must be in the Model instead of the Controller. So taking a look at our code we know we are not doing it well.

We can move some of the code from the Controller to the Model making use of the callback after_create. There is a good documentation about that and other people with much more talent than I have already written about this.
/app/controllers/users_controller.rb

class UsersController < ApplicationController
  def create
    @user = User.new(params[:user])
    if @user.save
      flash[:notice] = "Account registered!"
      redirect_back_or_default account_url
    else
      render :action => :new
    end
  end
end

/app/models/user.rb

class User < ActiveRecord::Base
  has_one :card

  after_create :create_card

  protected
    def create_card
      Card.create :user_id => id, :title => "Visit card of #{login}"
    end
end

But there’s even a better solution because having card creation code in the user controller doesn’t make much sense. Here is where observers come, “a great way to reduce the clutter that normally comes when the model class is burdened with functionality that doesn‘t pertain to the core responsibility of the class” as once again the documentation says. There’s also a very good article about this in Spanish. So we have to move the card creation to an user Observer, that handles it everytime an user is registered.
/app/models/user.rb

class User < ActiveRecord::Base
  has_one :card
end

/app/controllers/user_observer.rb

class UserObserver < ActiveRecord::Observer
  def after_create(user)
    Card.create :user_id => user.id, :title => "Visit card of #{user.login}"
  end
end

This is “the rails way”, Skinny Model Skinny Controller.

Finally I want to give thanks to the ror-es mailing list I signed up recently. I had the luck to work with some of the better rails developers in my past projects and now I have discovered that not only they were great but also the vast majority behind Ruby on Rails community is awesome. Thank you guys.

Update: I was using the restful_authentication plugin in order to manage the users authentication in the app, but as the comments say this is not the best solution. I have updated the code in order to handle this with the authlogic plugin, which is much better.