Common method in model and helper

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 %> 

Answer 2

If you do want to move it to a helper, you should move it in to the client_helper, as it is something just for your Client model and not for the whole application.

The method you speak of though, is it a static class method or an instance method? If it's an instance method, then your models (even if they're in views) can call that method. If it's a static class method, then your views can use it too by calling it like any other static class method (i.e, Client.do_method or something).

I don't see any reason why it needs to be in a helper, unless your method has absoloutely nothing to do with your model, in which case that would be a different question.