Engine routes in Application Controller

Question

I have a before_filter hook in my main app\'s application controller that does something like: (It doesn\'t just put a link in the flash, there is a message, but it isn\'t r

Answer 1

You can keep the isolate_namespace, as strongly recommended by Rails Engine guide, and do this:

# inside your main_app's config/routes.rb
Rails.application.routes.draw do
  root to: 'home#index'

  mount MyEngine::Engine, at: "/" 
end

# inside your engine's controller
module MyEngine
  class SomeController << ::ApplicationController
    # include main_app's route helpers
    helper Rails.application.routes.url_helpers

  end
end

And inside your gem, make sure all the url helpers are prefixed with the correct routing proxy method (e.g. my_engine.pages_path).

Your main_app's layout and engine's controller will route and link to those url helpers correctly to the main app. You don't have to add "main_app" prefix anywhere to the main app. The only downside is you're mounting your engine's routes at main_app's root path, which could collide with any routes by the same name. This is expected anyway if you were to do non-isolate_namespace.