Question

I have simple rails application. Create, delete, edit posts. And I need to rate this posts.
Where to place rate function, in model or controller? and why?

Answer 1

Usually this sort of thing plays out in both places. You’ll have a rate method on the model, and you’ll have a rate action in the controller.

Remember that it’s the controller’s primary function to receive requests, load the proper models, adjust them as necessary, and save the results. Often the models will implement the functionality required to facilitate this.

In the controller you’d make something like this:

class ItemsController < ApplicationController
  def rate
    @item.rate!(session[:user_id], params[:rating])
  end   
end

In the model you’d have something like this:

class Item < ActiveRecord::Base
  has_many :ratings

  def rate!(user_id, rating)
    self.ratings.create(:user_id => user_id, :rating => rating)
  end
end

Without a controller you can’t access the models, it has to go through that layer, and without a model you have no persistent data. They work together.