命名一个Rails has_many:through:多态关系

Question

我有一个问题设置Rails has_many:通过:多态关系.

我知道这个主题在SO上有很好的 文档,但我认为我的问题取决于我的模型和foreign_key名称,而不是语法,即我认为这是"我一直在看代码太长"的问题,只需要另一个一双眼睛.

无论如何,我有以下设置:

class Milestone < ActiveRecord::Base
  has_many :responsible_items, :as => :responsibility
  has_many :responsible, :through => :responsible_items
end

class ResponsibleItem < ActiveRecord::Base
  belongs_to :responsible, :class_name => "User"
  belongs_to :responsibility, :polymorphic => true
end

class User < ActiveRecord::Base
  has_many :responsible_items, :foreign_key => :responsible_id
  has_many :responsibilities, :through => :responsible_items
end

从里程碑方面来看,这似乎没有错误.例如在终端我可以写:

Milestone.first.responsible

......按照我的预期得到一个空集合.

但是,从用户方面来说,运行:

User.first.responsibilities

...正在返回AR错误:

ActiveRecord::HasManyThroughAssociationPolymorphicSourceError: Cannot have a has_many :through association 'User#responsibilities' on the polymorphic object 'Responsibility#responsibility'.

我假设这个问题与我将用户关系称为:负责人这一事实有关.这是正确的吗？

任何帮助将不胜感激,谢谢.

Answer 1

感谢@ Abid的评论,我开始考虑responsibilities为用户提供所有服务的物流,这是不可行的.我需要从关系中更加具体地了解我想要的东西,并且结果定义了以下工作:

class User < ActiveRecord::Base
  has_many :responsible_items, :foreign_key => :responsible_id
  has_many :milestone_responsibilities, :through => :responsible_items, :source => :responsibility, :source_type => 'Milestone'
end

然后,我可以扩展它,因为我在其他模型上添加了更多的多态关系,例如:

class User < ActiveRecord::Base
  has_many :responsible_items, :foreign_key => :responsible_id
  has_many :milestone_responsibilities, :through => :responsible_items, :source => :responsibility, :source_type => 'Milestone'
  has_many :task_responsibilities, :through => :responsible_items, :source => :responsibility, :source_type => 'Task'
end