What is the mechanism of 'end_of_association_chain' in 'Inherited resources' gem

Question

Inherited resources is a powerful gem that I can use it to avoid a lot of repeating things. But i still don't understand why it can get a object through end_of_association_chain even i did not pass anything related to its belongs_to model

Answer 1

Try to look into Rails routes. AFAIK end_of_association_chain constructs its value based on routes.

/book/1/pages -> you get the first book pages inside end_of_association_chain.

See also: https://github.com/activeadmin/inherited_resources#overwriting-defaults

The end_of_association_chain returns your resource after nesting all associations and scopes (more about this below).

I did not look into end_of_association_chain sourcecodes, but I guess that 'associations' and 'scopes' here mean exactly the route-constructing keywords like:

resource :production, only: [:update], controller: :production, selected_navigation_category: 'production', path: 'marketing' do
  resources :photos, only: %i[index update destroy] do
    collection do
      get 'set/:photo_set', to: :photo_set, as: :photo_set

I have a PhotosController#photo_set method which contains end_of_association_chain. I also was wondering - what is this value - until I dove into routes file.