lib/hypermodel/collection.rb
def parent_link
      link = {}
      if collection_hierarchy.length > 1
        parent_name = collection_hierarchy[-2].class.name.downcase
        link[parent_name] = {
          href: @controller.polymorphic_url(collection_hierarchy[0..-2])
        }
      end
      link
    end
def parent_link
      link = {}
      if collection_hierarchy.length > 1
        parent_name = collection_hierarchy[-2].class.name.downcase
        link[parent_name] = {
          href: @controller.polymorphic_url(collection_hierarchy[0..-2])
        }
      end
      link
    end
Internal: Returns a Hash with a link to the parent of the collection, if
 it exists, or an empty Hash otherwise.