====== Caching Nested Forms ======

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

<code>
  map.resources :guests, :has_many => :registrations
</code>


Produces:

<code>
    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"}
</code>
(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.

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

This produces:

<code>
    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"}                        
</code>

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)

[[http://adamblog.heroku.com/past/2007/12/20/nested_resources_in_rails_2/|Nested Resources in Rails 2]]