acts_as_resource lets you handle nested resource controllers neatly without having to modify every single call to a named route to include the full list of resources used to reach the target resource.

Consider a routing table like

    map.resources :albums do |album|
      album.resources :songs
    end

By configuring your models like

    class Album < ActiveRecord::Base
      has_many :songs
      acts_as_resource
    end

and

    class Song < ActiveRecord::Base
      belongs_to :album
      acts_as_resource :parent => :album
    end

You get a bunch of handy stuff. In your Song views, for instance, where before you had to do +song_path @song.album, @song+, you can now do: +song_path @song+ and the named route will use the ‘parent’ info to work out what objects are needed to build the path.

In your controllers meanwhile, you get a generic fetch_resources which automagically fetches the appropriate resources for the request, checking that they are properly accessible from the ‘base’ resource and assigns them to appropriately named instance variables (following the conventions used by the resource_scaffolding that comes with Rails 1.2.1).

You also get a new controller method, resource_chain, that you can use for writing generic actions. We don’t quite have enough support to replace the scaffold generated controller with simple inheritance, but we’re getting there.