Presenter < SimpleDelegator #ruby

nodes_presenter.rb

class NodesPresenter < SimpleDelegator
  def initialize(id_or_object)
    @node = id_or_object.is_a?(Integer) ? NodeDecorator.find(id_or_object) : id_or_object.decorate
    super @node
  end

  def ancestor(key)
    NodesPresenter.new(@node.ancestor(key))
  end

  def ancestors
    @ancestors ||= @node.ancestors.collect {|n| NodesPresenter.new(n)}
  end

  def breadcrumbs
    ancestors.select { |a| a.slug.present? }
  end

  def parent
    @parent ||= NodesPresenter.new(@node.parent) if @node.parent.present?
  end

  def children
    @children ||= @node.children.collect {|n| NodesPresenter.new(n)}
  end
end

usage.rb

node = NodesPresenter.new(Node.first)
# has_children? delegated to Node model
puts node.children if node.has_children?