Question

I’m trying to make logging for my rails app and have some dilemmas over philosophy used in rails. My app has Link model which has_many Hits:

class Link < AR::Base
  has_many :hits
end

class Hit < AR::Base
  belongs_to :link
end

Now each time the link is being hit, I call hit! method to record a request on the link (to keep the controller skinny I make the model fat):

class LinksController < ApplicationController
  def hit
    link = Link.find(params[:id])
    link.hit!(request)
  end
end

class Link < AR::Base
  def hit!(request)
    params = extract_data_from_request(request)
    hits.create(params)
  end
end

Now here’s where I’m confused. I want to record the data that came with request object (like remote ip, referrer, user agent, etc.) so I need to pass request object down to model, but I believe that this does not conform to “separation of concerns” and blurs responsibility lines in MVC design pattern (of course, correct me if I’m wrong). Also if I’ll create a Hit object in controller itself, then I’m making skinny model and fat controller:

class LinksController < ApplicationController
  def hit
    hit_params = extract_data_from_request(request)
    Hit.create(hit_params.merge(:link_id => params[:id])
  end
end

Although the latter case makes testing much easier (I don’t need to mock request in model specs) – it just doesn’t seem right.

Any advice on this – much appreciated.

P.S. extract_data_from_request(req) method is placed in appropriate places where needed. It returns a hash of needed attributes for Hit object.

Answer 1

Personally I would be wary of over-thinking these things too much.

The concept of a hit is very much tied to a website or web application, as is the concept of a (HTTP) request. The fat controller anti-pattern is more about having lengthy controller actions that contain ActiveRecord find statements and business logic (often characterised by if/elsif/else blocks) that can easily be extracted into the model.

Controllers have certain orchestration responsibilities. Creating an object within one isn’t a heinous crime. After all, we do it all the time in our create actions.