遇到問題：依賴=>：銷燬和實例變量

Question

我有一個項目有很多項目;它是:dependent => :destroy。 我在調用回調（特別是Item的after_destroy）時試圖告訴導軌，只有當Item被「單獨」銷燬時才運行，但所有項目都不被銷燬。 當整個項目被銷燬時，我實際上並不需要（項目的）這個after_destroy方法來運行。

我不想做:dependent => :delete，因爲Item中有許多其他關聯連接到它（與:dependent => :destroy）。

它爲我的作品只與類變量，但我希望它曾與一個實例變量工作：

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 

我能想到的是另一種選擇刪除:dependent => :destroy和手動處理破壞的項目after_destroy方法中的項目，但它似乎也太難看了，特別是因爲Project有許多項目類型:dependent => :destroy必須轉移到該方法。

任何想法，將不勝感激

Answer 1

如果您不需要使用刪除整個項目時回調，可以使用DELETE_ALL而不是破壞：

Rails :dependent => :destroy VS :dependent => :delete_all

Answer 2

我希望這不是最好的解決方案，但至少它的工作原理並沒有通過類變量引入任何全局狀態：

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