Route-aware resource_path?

[contentfree]

I have a resource – Conversation – that has a polymorphic to a couple other models – Campaign, Subscriber.

My routes look something like:

resources :conversations
resources :campaigns do
  resources :conversations, only: :index 
end
resources :subscribers do
  resources :conversations, only: :index
end

My ConversationsController contains:

belongs_to :campaign, :subscriber, optional: true

When I visit /campaigns/1/conversations and show the list of related conversations, I want to have a link to edit or destroy a Conversation.

However, resource_path fails with undefined method 'campaign_conversation_path' because that route is not available (on purpose).

How do I get resource_path to be aware of the available routes?

[contentfree]

It seems possible that the undocumented shallow option for belongs_to could be leveraged here (though adding it to my belongs_to causes an error '@' is not allowed as an instance variable name). ShallowHelpers doesn't include any routing methods though.

[contentfree]

What about adding only support to belongs_to? Something like belongs_to :campaign, :subscriber, optional: true, only: [:index]? (Not sure how except would be supported though)

[contentfree]

Thoughts @javierjulio ?