class Entity < ActiveRecord::Base
  has_many :relationships, :foreign_key => "left_id"
  has_many :relationships, :foreign_key => "right_id"
  has_many :rights, :through => :relationships
  has_many :lefts, :through => :relationships
end

class Individual < Entity
end

class Organisation < Entity
end

class Relationship < ActiveRecord::Base
  has_one :relationshiptypes
  belongs_to :left, :class_name => "Entity", :foreign_key => "left_id"
  belongs_to :right, :class_name => "Entity", :foreign_key => "right_id"
  validates_uniqueness_of :left_id, :scope => [:right_id, :relationshiptypes_id], :message => "This relationship already exists"
end

class Relationshiptype < ActiveRecord::Base
  belongs_to :relationships
end