ruby-on-rails - 无法在 Rails 应用程序中保存关联对象的属性

Question

我有三个模型定义如下

class Student < ActiveRecord::Base
  belongs_to :user
  has_many :placements
  has_many :companys , through: :placements
end

class Company < ActiveRecord::Base
    has_many :placements
    has_many :students , through: :placements
end

class Placement < ActiveRecord::Base
  belongs_to :student
  belongs_to :company

  before_save  :set_placed

  def set_placed
    s = self.student
    s.is_placed = true
    s.save
  end
end

每次我为放置对象添加数据时，我都想更新其相应学生对象中的字段。但是当我使用 rails_admin 添加数据时，我收到错误 Placement failed to be created 。

当我删除 before_save 调用时，可以添加数据。

我正在使用 better_errors gem 进行调试。我从中得到以下信息

@_already_called    

{[:autosave_associated_records_for_student, :student]=>false, 
 [:autosave_associated_records_for_company, :company]=>false}

我希望这可能是错误的原因。

我该如何解决这个错误？

Answer 1

You have a s.save in your set_placed callback. You don't save an ActiveRecord object in a callback, and especially not in a before_save callback.

Answer 2

尝试这个，

def set_placed
  self.student.is_placed = true
end