Advanced Rails , Database Chapter memo(3)

Composite Keys
你需要的是composite_primary_keys

<br />#安裝<br />gem install composite_primary_keys<br /><br />#require 進來<br />require 'composite_primary_keys'<br /><br />#設定<br />class Order < ActiveRecord::Base<br /> set_primary_keys :node_id, :order_id<br /> has_many :line_items, :foreign_key => [:order_node_id, :order_id]<br />end<br /><br />class LineItem < ActiveRecord::Base<br /> set_primary_keys :node_id, :line_item_id<br /> belongs_to :order, :foreign_key => [:order_node_id, :order_id]<br />end<br /><br />#可以看到<br />Order.primary_key # => [:node_id, :order_id]<br />Order.primary_key.to_s # => "node_id,order_id"<br />Order.find 1, 5 # => #<Order:0x1234567 @attributes={"node_id"=>"1", "order_id"=>"5"}><br />