Question

I have an action called update_mobile and in it I am preparing a massive amount of instance variables that I use in a RABL JSON request. You can see that if the request contains the params[:last_updated] parameter, then I only get the models that have been updated since then. This seems to disobey the “Fat Models, Skinny Controllers” method. How can I refactor this method?

  def update_mobile
    @last_updated = params[:last_updated]
    if @last_updated.nil?
      @buddies = @user.friends
      @courses = @user.courses
      @friendly_schools = @user.friendly_schools
      @documents = @user.all_notes
      @instructors = @user.current_instructors
      @friendships = @user.friendships
      @questions = @user.current_questions
      @answers = @user.current_answers
      @comments = @user.current_comments
    else
      @buddies = @user.friends.select{ |user| user.updated_at > @last_updated }
      @courses = @user.courses.select{ |course| course.updated_at > @last_updated }
      @friendly_schools = @user.friendly_schools.select{ |school| school.updated_at > @last_updated }
      @documents = @user.all_notes.select{ |note| note.updated_at > @last_updated }
      @instructors = @user.current_instructors.select{ |instructor| instructor.updated_at > @last_updated }
      @friendships = @user.friendships.select{ |friendship| friendship.updated_at > @last_updated }
      @questions = @user.current_questions.select{ |question| question.updated_at > @last_updated }
      @answers = @user.current_answers.select{ |answer| answer.updated_at > @last_updated }
      @comments = @user.current_comments.select{ |comment| comment.updated_at > @last_updated }
    end
  end

Answer 1

You should move the code out to your model and let your model deal with 1) the parameter being nil and 2) using ActiveRecord to query the database effectively.

In your controller, have lines like this for each of your variables:

@friends = @user.friends.updated_since(params[:last_updated])

(I’ve renamed @buddies here to @friends, because we want to maintain consistency in naming the things of the system)

Then, in your Friend model, define a class method called updated_since that does that logic:

class Friend < ActiveRecord::Base
  def self.updated_since(last_updated)
    if last_updated.present?
      where("updated_at > ?", last_updated)
    else
      all
    end
  end
end