class Dwarf < ActiveRecord::Base
  belongs_to :mountain
  belongs_to :spouse,
             :class_name => "Dwarf",
             :foreign_key => "spouse_id"
  has_one    :king_of,
             :class_name => "Mountain",
             :foreign_key => "king_id"
  has_one    :spouse_of,
             :class_name => "Dwarf",
             :foreign_key => "spouse_id"
  has_and_belongs_to_many :visited_mountains,
                          :class_name => "Mountain",
                          :join_table => "visits"
  validates_presence_of :name, :born
  validates_numericality_of :born
end