Posted by nanki Tue, 25 Apr 2006 14:30:00 GMT composite_primary_keys 主キーとして複合キーを扱える。 $ gem install composite_primary_keys require 'composite_primary_keys' class Road < ActiveRecord::Base belongs_to :attribute, :foreign_key => [:attribute_code, :mesh_code] end class Attribute < ActiveRecord::Base set_primary_keys :attribute_code, :mesh_code end Road.find(:first).attribute #=> SELECT...WHERE roads.a