Question

我有以下型号：

class Group < ActiveRecord::Base
    has_many :threads, :dependent => :destroy

class Thread < ActiveRecord::Base
    has_many :comments, :as => :commentable, :dependent => :destroy

 class Comment < ActiveRecord::Base
    belongs_to :commentable, :polymorphic => true
    acts_as_nested_set

我遇到的问题是当用户删除某个组时，所有类型的注释都被破坏或删除。我看了一下日志，这就是发生的事情：

Comment Load (0.8ms)  SELECT "comments".* FROM "comments" WHERE ("comments".commentable_id = 101 AND "comments".commentable_type = 'Thread') ORDER BY comments.created_at DESC
AREL (0.9ms)  DELETE FROM "comments" WHERE ("comments"."lft" > 649 AND "comments"."rgt" < 650)
AREL (0.4ms)  UPDATE "comments" SET "lft" = ("lft" - 2) WHERE ("lft" > 650)
AREL (0.5ms)  UPDATE "comments" SET "rgt" = ("rgt" - 2) WHERE ("rgt" > 650)
AREL (0.2ms)  DELETE FROM "comments" WHERE ("comments"."id" = 381)
AREL (0.4ms)  DELETE FROM "comments" WHERE ("comments"."lft" > 645 AND "comments"."rgt" < 646)
AREL (0.4ms)  UPDATE "comments" SET "lft" = ("lft" - 2) WHERE ("lft" > 646)
AREL (0.4ms)  UPDATE "comments" SET "rgt" = ("rgt" - 2) WHERE ("rgt" > 646)
AREL (0.2ms)  DELETE FROM "comments" WHERE ("comments"."id" = 380)
AREL (0.3ms)  DELETE FROM "comments" WHERE ("comments"."lft" > 648 AND "comments"."rgt" < 651)
AREL (0.3ms)  UPDATE "comments" SET "lft" = ("lft" - 4) WHERE ("lft" > 651)
AREL (0.3ms)  UPDATE "comments" SET "rgt" = ("rgt" - 4) WHERE ("rgt" > 651)
AREL (0.2ms)  DELETE FROM "comments" WHERE ("comments"."id" = 379)
AREL (0.3ms)  DELETE FROM "comments" WHERE ("comments"."lft" > 644 AND "comments"."rgt" < 647)
AREL (0.4ms)  UPDATE "comments" SET "lft" = ("lft" - 4) WHERE ("lft" > 647)
AREL (0.4ms)  UPDATE "comments" SET "rgt" = ("rgt" - 4) WHERE ("rgt" > 647)
AREL (0.2ms)  DELETE FROM "comments" WHERE ("comments"."id" = 378)
AREL (0.4ms)  DELETE FROM "comments" WHERE ("comments"."lft" > 642 AND "comments"."rgt" < 643)
AREL (0.8ms)  UPDATE "comments" SET "lft" = ("lft" - 2) WHERE ("lft" > 643)
AREL (0.4ms)  UPDATE "comments" SET "rgt" = ("rgt" - 2) WHERE ("rgt" > 643)
AREL (0.2ms)  DELETE FROM "comments" WHERE ("comments"."id" = 377)
AREL (0.7ms)  DELETE FROM "comments" WHERE ("comments"."lft" > 641 AND "comments"."rgt" < 652)
AREL (0.9ms)  UPDATE "comments" SET "lft" = ("lft" - 12) WHERE ("lft" > 652)
AREL (0.9ms)  UPDATE "comments" SET "rgt" = ("rgt" - 12) WHERE ("rgt" > 652)
AREL (0.3ms)  DELETE FROM "comments" WHERE ("comments"."id" = 376)
AREL (0.4ms)  DELETE FROM "threads" WHERE ("threads"."id" = 101)
AREL (0.4ms)  DELETE FROM "groups" WHERE ("groups"."id" = 57)

这是嵌套行为的正常行为吗？我希望只有DELETE FROM COMMENTS，其中Comment.id = XXXX。但相反，所有这一切都在进行，评论记录正在破裂。

有没有人见过这个？

谢谢

更新w用于防止深度嵌套的内容：

  after_save :ensure_max_nestedset_level
  def ensure_max_nestedset_level
    if self.level > 2
      self.move_to_child_of(parent.parent)
    end
  end

Answer 1

这不应该打破记录。删除节点时，必须修剪树。 The comments in acts_as_nested_set说

“添加和删除条目都需要全表写入。”

this before destroy method in acts_as_nested_set中的代码在您删除Comment记录时尝试重新组织表，并且是正常行为。

Answer 2

好吧，它显然是在删除节点时尝试维护层次结构，这是SQL中的一个常见问题。

您使用的是哪个库？真棒嵌套？为什么会导致记录损坏我不确定。

您可以在此处阅读有关嵌套集方法的更多信息：

http://mikehillyer.com/articles/managing-hierarchical-data-in-mysql/

请参阅下面的“嵌套集模型”部分和“已删除的节点”子部分，了解删除的原因。

因此删除语句将是正常行为。

Answer 3

似乎不太可能，但绝不可能，您使用的gem无法删除项目并保持嵌套正确。因此，它与您正在做的事情有关。它也可能与多态关系有关。

您是否删除了ensure_max_nestedset_level进行测试？那会有用吗？删除单个评论时是否有效？删除父评论？（在它下面嵌套元素）。它是否只在删除组/线程时失败？

Answer 4

简单acts_as_nested_set为评论表中的所有记录创建一个树。我猜你应该为每个帖子创建一个评论树。例如。 acts_as_nested_set :parent_column => :parent_id, :scope => [:commentable_id, :commentable_type]。

另请注意，默认由acts_as_nested_set创建的关联将:dependent设置为:delete_all。因此，请确保:parent_id设置正确。

删除组时进行上述修改，只应删除属于该组的注释（通过线程）。

BTW我使用awesome_nested_set推荐的ruby-toolbox。

Rails - 注释w acts_as_nested_set - 删除依赖记录时正在删除销毁数据

4 个答案: