Skinny Controllers and Overweight Models
17 August 2008
All Rails developers know the slogan “Skinny Controllers, Fat Models” and I heartily agree with it. Every conference you go to, you hear it. But there’s a problem! My Fat models got overweight!
What happened? By stuffing all applications logic in the Models, they become fat, very fat. Although this is supposed to be a good thing, I don’t like it. My models get so fat that it takes me forever to scroll through it and find the method I’m working on. There must be a better way!
Well, yes there is: create modules! Normally you’d write a module to reuse your code in different places, but there’s no rule that says you may not use a module only once.
So, I package all related code (e.g. Authentication, state management, managing associated objects, etc) into different modules and place them in the /lib directory. Let’s say you have a a bunch of methods to handle keep a counter on your User model
class User < ActiveRecord::Base attr_accessor :counter def up counter += 1 end def down counter -= 1 end def reset counter = 0 end end
You could create a new file lib/counter.rb and include that module in your User model.
class User < ActiveRecord::Base attr_accessor :counter include Counter end module Counter def up counter += 1 end def down counter -= 1 end def reset counter = 0 end end
As you can see, this keeps your fat User model clean and makes it easier for you to find code that applies to a certain function.