Question

I am using Ruby on Rails 3.2.2 and I would like to know what is a common approach in order to handle associated objects of a has_many :through ActiveRecord::Association. That is, I have:

class User < ActiveRecord::Base
  has_many :article_editor_associations, :class_name => 'Articles::UserEditorAssociation'
  has_many :articles, :through => :article_editor_associations
end

class Article < ActiveRecord::Base
  has_many :user_editor_associations, :class_name => 'Articles::UserEditorAssociation'
  has_many :editor_users, :through => :user_editor_associations
end

class Articles::UserAssociation < ActiveRecord::Base
  belongs_to :editor_users
  belongs_to :articles
end

By using the above code, I can run the @article.editor_users method so to retrieve an Array of Editor Users. However, in order to make things to fit better with my application (that is, for example, in order to handle things like I18n translations and similar in a “programmatic” way), I am thinking to add to my application a new model like the following:

class EditorUser < User # Note the class name and the class inheritance
  ...
end

This way, through my application, I can refer to the EditorUser class in order to handle article “editor user” instances as if they were User objects… more, since inheritance, in the EditorUser class I can state “specific methods” (for example, scope methods) available only to EditorUser instances (not to User instances)…

Is it a “common” approach to make things as I would like to make in my case? Is it the “Rails Way”? If so, what I could / should make to handle this situation? If no, how could / should I proceed?

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In other words, I thought using class EditorUser < User ... end because associated EditorUser objects (retrieved by running the @article.editor_users method) are User objects. I think that by stating a EditoUser class in the app/models directory (or elsewhere) could simplify things in my application because you can work around that constant name (for example, you can “play” with that constant name in order to “build” translation strings or by stating new methods just to be used for EditorUser instances).

Answer 1

With Rails, I’ve learned to focus on the naming conventions and standard usage first (‘convention’ over configuration) and would set it up like this:

class User < ActiveRecord::Base
  has_many :editors
  has_many :articles, :through => :editors
end

class Article < ActiveRecord::Base
  has_many :editors
  has_many :users, :through => :editors
end

class Editor < ActiveRecord::Base
  belongs_to :user
  belongs_to :article
end

You can either use the presence of the join record, e.g. User.editor or add an additional attribute to editor if you want different editor access levels.

The above does not fully answer your question perhaps but should be a good starting point. I say this because one of the most important things about rails is that it uses a principle of ‘convention over configuration’. This is good as it leads to terse, minimalist code. It’s bad because you have to learn all the zillion conventions. If you don’t know them or the framework well you can get yourself into a whole heap of trouble as I have seen with many rails applications that I have worked on over the years.

So my advice is really to step back. Don’t try and force things to work with things like class renames. If the setup I have shown doesn’t meet your needs, revisit your needs and read more on active record and associations in the API. I know this can be kinda frustrating for quite a while with rails but you really need to look how to do things the right way if you’re going to be a good rails programmer in the long term.