由於舊的oracle 資料庫Table內沒有 id 這個標準 ActiveRecord 要求的主鍵欄,可採用 composite_primary_keys.gem 來解決問題。ruby
下載並安裝 gem 後,於 environment.rb 加入:oracle
require 'composite_primary_keys'
使用範例:ui
set_primary_keys :user_id, :group_id class Membership < ActiveRecord::Base # set_primary_keys *keys - turns on composite key functionality belongs_to :user belongs_to :group has_many :statuses, :class_name => 'MembershipStatus', :foreign_key => [:user_id, :group_id] end