ruby-on-rails - 与 has_many 建立关联 :through in multiple models

Question

请帮助理解如何@project.payments拥有这棵树:

Project
   |__Stages
         |__Costs
              |__Payments

项目.rb

 has_many :stages
 has_many :costs, :through => stages

舞台.rb

belongs_to :project
has_many :costs
has_many :payments :through => costs

成本.rb

belongs_to :stage
has_many :payments

支付.rb

belongs_to :cost

Answer 1

注意:因为这是一个嵌套的 has_many :through 关系，它只能在 Rails 3.1+ 中工作(3.1 的 RC4 已经过时)

项目.rb

has_many :payments, :through => costs