ruby-on-rails-4 - Rails4 : How to trigger the callback for attr_accessor while using accepts_nested_attributes_for

Question

请检查伪代码:

class Team
  has_many :users
  accepts_nested_attributes_for :users, allow_destroy: true
end

class User
  belongs_to :team
  has_many :addresses
  accepts_nested_attributes_for :addresses
  attr_accessor :dummy

  before_validation :generate_addresses_attributes
  def generate_addresses_attributes
    # Use the dummy value to set the addresses_attributes
  end
end

现在执行 team.update(users_attributes: [{"0" => { dummy: "changed!" }}]) (除了虚拟属性，其他字段不会改变)，它不会触发#generate_addresses_attributes 回调，因为它认为没有任何变化，没有保存，没有回调......

所以我的问题是如何触发虚拟属性的回调，或者强制保存 accepts_nested_attributes_for。

谢谢!

Answer 1

最后，我找到了两个解决方案:

在团队模型中添加回调以手动触发回调功能

使用 attribute_will_change!覆盖 setter 方法:

class User
  belongs_to :team
  has_many :addresses
  accepts_nested_attributes_for :addresses
  attr_accessor :dummy

  def dummy=(value)
    attribute_will_change!("dummy") if @dummy != value
    @dummy = value
  end

  ...
end