ruby-on-rails - 遇到 :dependent => :destroy and Instance variables 问题

Question

我有一个包含很多项的项目；它是 :dependent => :destroy。我试图在调用回调(特别是 Item 的 after_destroy)时告诉 rails，仅当 Item 被“单独”销毁时才运行，但所有项目都没有被销毁。当整个项目被销毁时，我实际上根本不需要这个after_destroy方法(Item)来运行。

我不想执行 :dependent => :delete 因为 Item 有许多其他关联与之相关(使用 :dependent => :destroy)。

它只适用于类变量，但我希望它适用于实例变量:

class Project < ActiveRecord::Base
  has_many :items, :dependent => :destroy
  before_destroy :destroying_the_project

  def destroying_the_project
    # this is a class variable, but I wish I could had @destroying_me 
    # instead of @@destroying_me. 
    @@destroying_me = true
  end

  def destroying_the_project?
    @@destroying_me
  end
end

class Item < ActiveRecord::Base
  belongs_to :project
  after_destroy :update_related_statuses

  def update_related_statuses
    # I with I could had return if project.destroying_the_project?
    # but since the callback gets the project from the DB, it's another instance,
    # so the instance variable is not relevant here
    return if Project::destroying_the_project?

    # do a lot of stuff which is IRRELEVANT if the project is being destroyed. 
    # this doesn't work well since if we destroy the project, 
    # we may have already destroyed the suites and the entity
    suite.delay.suite_update_status 
    entity.delay.update_last_run
  end
end

我能想到的另一个选择是删除 :dependent => :destroy 并手动处理项目 after_destroy 方法中项目的销毁，但它似乎也太丑陋了，特别是因为 Project 有许多带有 :dependent => :destroy 的项类型，它们必须转移到那个方法。

任何想法将不胜感激

Answer 1

我希望这不是最好的解决方案，但至少它可以工作并且不会通过类变量引入任何全局状态:

class Project < ActiveRecord::Base
  has_many :items
  before_destroy :destroying_the_project

  def destroying_the_project
    Rails.logger.info 'Project#destroying_the_project'
    items.each &:destroy_without_statuses_update
  end
end

class Item < ActiveRecord::Base
  belongs_to :project
  after_destroy :update_related_statuses, 
                :unless => :destroy_without_statuses_update?

  def update_related_statuses
    Rails.logger.info 'Item#update_related_statuses'
  end

  def destroy_without_statuses_update
    @destroy_without_statuses_update = true
    destroy
  end

  def destroy_without_statuses_update?
    !!@destroy_without_statuses_update
  end
end