Caching Nested Forms

Normally, using a nested resource's url leads you to the controller of the “embedded” resource. E.g:

  map.resources :guests, :has_many => :registrations

Produces:

    guest_registrations GET    /guests/:guest_id/registrations(.:format)           {:controller=>"registrations", :action=>"index"}
                        POST   /guests/:guest_id/registrations(.:format)           {:controller=>"registrations", :action=>"create"}
 new_guest_registration GET    /guests/:guest_id/registrations/new(.:format)       {:controller=>"registrations", :action=>"new"}
edit_guest_registration GET    /guests/:guest_id/registrations/:id/edit(.:format)  {:controller=>"registrations", :action=>"edit"}
     guest_registration GET    /guests/:guest_id/registrations/:id(.:format)       {:controller=>"registrations", :action=>"show"}
                        PUT    /guests/:guest_id/registrations/:id(.:format)       {:controller=>"registrations", :action=>"update"}
                        DELETE /guests/:guest_id/registrations/:id(.:format)       {:controller=>"registrations", :action=>"destroy"}

(You can output this yourself using rake routes)

This is obviously bad if you want to use nested forms, where you need the controller to be the one for the parent object. In a nested form, the CRUD (Create, Read, Update, Delete) actions on the nested model are automatically handled for you, so there's no real need to access the nested model's controller.

  map.resources :guests do |guest|
    guest.resources :registrations, :path_prefix => ':locale/guests/:guest_id', :controller => :guests
  end

This produces:

    guest_registrations GET    /guests/:guest_id/registrations(.:format)           {:controller=>"guests", :action=>"index"}
                        POST   /guests/:guest_id/registrations(.:format)           {:controller=>"guests", :action=>"create"}
 new_guest_registration GET    /guests/:guest_id/registrations/new(.:format)       {:controller=>"guests", :action=>"new"}
edit_guest_registration GET    /guests/:guest_id/registrations/:id/edit(.:format)  {:controller=>"guests", :action=>"edit"}
     guest_registration GET    /guests/:guest_id/registrations/:id(.:format)       {:controller=>"guests", :action=>"show"}
                        PUT    /guests/:guest_id/registrations/:id(.:format)       {:controller=>"guests", :action=>"update"}
                        DELETE /guests/:guest_id/registrations/:id(.:format)       {:controller=>"guests", :action=>"destroy"}                        

Now to be sure, following the example above you'll have to make distinction in your controller between cases where the registration id is known (all operations are on a specific registration), and where it is not (all operations pertain to a guest object). But you'd have to do that too if you were using a custom made “selected_registration_id”.

TO DO: include info on nested resources (routing)

Nested Resources in Rails 2