Question

I have a common method that exists in my model because it is called by my model. Retrospectively, my view also requires this model method. In order to accomplish this, I have:

1. moved the model method to the application_helper.rb file
2. my model calls the application_helper method by adding include ApplicationHelper at the top of my ActiveRecord model

Functionality wise, it works. But is this good practice?

My Model looks like this:

class Client < ActiveRecord::Base
  include ApplicationHelper
end

Answer 1

Writing include ApplicationHelper in to your model is bad practice because ApplicationHelper is a nice place to put tons of helper functions you need in your views. These functions will end up being imported as instance methods of your model. These functions are mostly unrelated to your model and will not work if they depend on things like params or request. Here are two other options:

Option 1:

You can just define the method inside the Client class, and then call it from the view, like this:

class Client < ActiveRecord::Base
    def self.my_class_method
    end
    def my_instance_method
    end
end

And then in your view:

<%= Client.my_class_method %>
<%= @client.my_instance_method %>

Option 2:

Make a separate module in lib and include it in the places you need it. The file name should match the module name for auto-loading to work.

In lib/my_module.rb:

module MyModule
    def my_method
    end
end

In your model:

class Client < ActiveRecord::Base
    include MyModule
    def other_method
      my_method
    end
end

Include the module in ApplicationHelper so it is available to all your views:

module ApplicationHelper
    include MyModule
end

Then in your view you can call it easily:

<%= my_method %>