Question

我一直在修改在线Rails教程以满足我的特定需求，而且我已经发现自己超出了我的深度。一点点清晰度将非常感激。我的代码低于我的问题。

此时，dan和rob是User类的实例，我打电话

dan.add_supervisor(rob)

然后它返回一个空集合：

dan.supervisors
=> #<ActiveRecord::Associations::CollectionProxy []>

然而，监督本身已经创建：

dan.initiated_supervisions
=> #<ActiveRecord::Associations::CollectionProxy [#<Supervision id: 50, supervisor_id: 68, supervisee_id: 67, created_at: "2015-03-10 18:30:01", updated_at: "2015-03-10 18:30:01">]>

理想的行为是has_many :through行为正常运行，并且能够通过调用dan.supervisors获取Dan的主管列表。为实现这一目标，我需要做出哪些改变？

User.rb

...

# Supervisees can choose their supervisors, 
# but not the other way around.

has_many :initiated_supervisions,     class_name: "Supervision", 
                                      foreign_key: "supervisee_id", 
                                      dependent: :destroy
has_many :non_initiated_supervisions, class_name: "Supervision", 
                                      foreign_key: "supervisor_id", 
                                      dependent: :destroy

has_many :supervisees, through: :non_initiated_supervisions
has_many :supervisors, through: :initiated_supervisions

...

def add_supervisor(other_user)
  initiated_supervisions.create(supervisor_id: other_user.id)
end

...

Supervision.rb

...

belongs_to :supervisor,    class_name: "User"
belongs_to :supervisee,    class_name: "User"
validates  :supervisor_id, presence:   true
validates  :supervisee_id, presence:   true

...

Answer 1

解决方案（暂时......请，请继续工作......）在两个class_name: "User"模型关联中指定User：

has_many :supervisors, through: :initiated_supervisions, class_name: "User"
has_many :supervisees, through: :non_initiated_supervisions, class_name: "User"

适用于自联接类的ActiveRecord关联

1 个答案: