Grab host app active record objects when engine and host app have same model names

Question

I have a host app unicorn with the model Article .

I also have a mountable engine hooked into the host app called blorgh . It also has a model: Article . It is namespaced, so the table name for the engine's Article is actually blorgh_articles .

While inside the engine I want to grab the host app's article , not the engine's article . Is this possible?

#blorgh/app/controllers/blorgh/articles_controller.rb
require_dependency "blorgh_application_controller"
module Blorgh
  class ArticlesController < ApplicationController
    def index
      @articles = Article.all #properly grabs all the engine's articles
      @host_app_articles = main_app.Article.all # this doesn't work. It should grab the host app's articles.
    end
    ...
  end
end

Answer 1

Use ::Article to refer to the top-level namespace class, and MyEngine::Article to refer to the engine's class.

While using Article alone within the MyEngine namespace will resolve correctly, doing this introduces a couple of pitfalls:

• It makes it confusing to understand your code as there are multiple references to an ambiguous Article .
• If you ever rename your MyEngine::Article class to something else, but miss a reference to Article during this change, the same code will now change in meaning to refer to the global ::Article . This may or may not break your specs, and it may introduce unintended behavior.