I’ve been messing around with mountable engines and I crossed a dilemma that I am sure you faced when implementing them, what should ApplicationController inherit from? Today each engine has a unique, name spaced ApplicationController, all of which inherit from ActionController::Base, then all of the controllers in each engine inherit from their corresponding ApplicationController. I understand the need to set up the engines this way so that they can run outside of the main_app, but all of the controllers in Rails inherit from ApplicationController because they need to share code. What primarily comes to mind are authentication methods and session variables, i.e. current_user. So when creating a Rails app that uses mountable engines, it is nice for all of the things to access a common ancestor. One solution is to include modules in ActionController::Base, as it is a common ancestor to all the controllers in the app. This process is outlined in this blog:
While this works it has in my opinion two problems –
there is not a convention on where to put the module that gets included on ActionController::Base
because the module gets included on initialization, you have to restart your Rails app for any changes to take effect
What I have done to combat these issues is create an EnginesController that inherits from ActionController::Base, then have each of my engines’ ApplicationControllers inherit from EnginesController. This seems to solve the above issues as long as EnginesController is in the load path.
So my questions for the group are, does this seem like a reasonable solution or am I missing something like, this is why ActionController::Base exists and why don’t you just open class it in the load path for the same effect? And if this is a reasonable approach, is it worth considering a convention on where to put files that are shared among mountable engines and the main_app?
Thanks for your time and thoughts,