module ActiveRecord::Associations

def association(name) # :nodoc:
  association = association_instance_get(name)
  if association.nil?
    unless reflection = self.class._reflect_on_association(name)
      raise AssociationNotFoundError.new(self, name)
    end
    association = reflection.association_class.new(self, reflection)
    association_instance_set(name, association)
  end
  association
end