Self ref

gistfile1.rb

class Company < ActiveRecord::Base
  attr_accessible :name 

  has_many :parent_associations, :class_name => 'Association', :foreign_key => 'child_id'
  has_many :child_associations, :class_name => 'Association', :foreign_key => 'parent_id'

  has_many :parents, :through => :parent_associations, :source => :parent
  has_many :children, :through => :child_associations, :source => :child
end