class Layout include Mongoid::Document include Mongoid::Timestamps field :name, :index => true field :description field :content references_many :children, :class_name => "Item" validates_presence_of :name validates_format_of :name, :with => /^[0-9a-zA-Z\-_]+$/ validates_uniqueness_of :name def self.exist_one? Layout.count > 0 end end