+ has_many :way_nodes, :foreign_key => 'id', :order => 'sequence_id'
+ has_many :nodes, :through => :way_nodes, :order => 'sequence_id'
+
+ has_many :way_tags, :foreign_key => 'id'
+
+ has_many :containing_relation_members, :class_name => "RelationMember", :as => :member
+ has_many :containing_relations, :class_name => "Relation", :through => :containing_relation_members, :source => :relation, :extend => ObjectFinder
+
+ validates_presence_of :id, :on => :update
+ validates_presence_of :changeset_id,:version, :timestamp
+ validates_uniqueness_of :id
+ validates_inclusion_of :visible, :in => [ true, false ]
+ validates_numericality_of :changeset_id, :version, :integer_only => true
+ validates_numericality_of :id, :on => :update, :integer_only => true
+ validates_associated :changeset