+ belongs_to :user
+
+ has_many :old_nodes
+ has_many :old_ways
+ has_many :old_relations
+
+ validates :title, :presence => true, :characters => true
+ validates :description, :presence => true, :characters => true
+ validates :description_format, :inclusion => { :in => %w[text html markdown] }
+
+ # this method overrides the AR default to provide the rich
+ # text object for the description field.
+ def description
+ RichText.new(self[:description_format], self[:description])
+ end