Change ruby on rails controller to respond differently based on route nesting - ruby-on-rails

Question

Is it possible to have a controller that interacts in a standard way at both the top level and also the nested level? Or will static routes need to be configured?
When I visit the first address /list/:list_id/items I want it to follow the nested_index method to display only a subset of the listed items (The items that belong to the list).
http://localhost:3000/list/:list_id/items
When I visit the below (/items) address I want it to show the whole list of items.
http://localhost:3000/items
/app/controllers/items_controller.rb
def index
#Item = Item.all
respond_to do |format|
format.html # index.html.erb
format.json { render json: #Item }
end
end
def nested_index
#list = List.find(params[:list_id])
#items = #list.items.paginate(page: params[:page], per_page: 5)
respond_to do |format|
format.html # index.html.erb
format.json { render json: #list }
end
end
/config/routes.rb
AppName::Application.routes.draw do
resources :list do
resources :items
end
end
# Do I need to add further routes here?

Answer 1

Personally, I think you should split this out into two separate controllers.
The index method of your controller should be designed to do just one thing. In the case of your nested route it should be fetching all the items appropriate for the selected list and passing them to the appropriate view. In the other instance it is fetching all items and (probably) passing them to a completely different view.
It seems you're trying to get one controller to do the job of two, simply for the sake of the controller's name.
I'd suggest creating an apps_controller and use that to collect all your items and display them, and leave your items_controller for its nested use.
Remember you don't need to name a controller after the model it interacts with ... rather, you should name it after the function it is responsible for. A controller which receives an activation code for a user account might update an is_active boolean on a User model, but you would call this controller Activations since that is what it does.
If you have lots of overlap between controllers you can move their code into modules and then include those modules in both controllers. This way you can DRY up your code whilst keeping the logic separate where necessary.
Take a look at these links for some ideas on code extraction:
http://railscasts.com/episodes/398-service-objects
http://railscasts.com/episodes/416-form-objects
But before you start refactoring all of your code into modules ... consider whether it adds anything to your codebase. Does it make things simpler? Does it make things more readable? Does it save you anything other than typing out a few more lines? If there's no benefit to refactoring ... just don't do it.

Answer 2

#Jon is right. This should be split into several different controllers:
# app/controllers/items_controller.rb
class ItemsController < ApplicationController
# default RESTful actions to operate on lists, for example #index
def index
#Item = Item.all
respond_to do |format|
format.html
format.json { render json: #item }
end
end
end
# app/controllers/lists_controller.rb
class ListsController < ApplicationController
# default RESTful actions to operate on lists
end
# app/controllers/lists/items_controllers.rb
class Lists::ItemsController < ApplicationController
def show
#list = List.find(params[:list_id])
#items = #list.items.paginate(page: params[:page], per_page: 5)
respond_to do |format|
format.html
format.json { render json: #items }
end
end
end
Routes:
AppName::Application.routes.draw do
resources :items
resources :lists do
resources :items
end
end