删除孤立的父级

问题描述

我有这样的关系:

Parent
  has_many :children

Child
  belongs_to :parent

如果没有更多的孩子，我想要做的是删除父级.所以要做到这一点，我有:

What I want to do is to delete the parent if there are no more children left. So to do this I have:

Child
    before_destroy :destroy_orphaned_parent

    def destroy_orphaned_parent
      parent.children.each do |c|
        return if c != self
      end
      parent.destroy
    end

这很好用，但是我也想将父级的删除级联到子级.例如.我通常会这样做:

This works fine, however I also want to cascade the delete of the parent to the child. E.g. I would normally do:

Parent
  has_many :children, :dependent => :destroy

这会导致 WebRick 服务器在我测试时崩溃.我认为这是由于最后一个孩子删除父删除子等的无限循环.

This causes the WebRick server to crash when I test it. I assume this is due to an infinite loop of the last child deleting the parent deleting the child etc.

我开始认为有更好的方法来做到这一点?有人有想法么?有没有办法防止这种递归?

I am starting to think that there is a better way to do this? Anyone have any ideas? Is there a way to prevent this recursion?

推荐答案

一些想法:

• 你可以删除孤儿的父母一个 after_destroy(使用像那个一样的声明http://groups.google.com/group/rubyonrails-talk/browse_thread/thread/a3f12d578f5a2619)

• You could delete orphaned parents inan after_destroy (find them using astatement like the one onhttp://groups.google.com/group/rubyonrails-talk/browse_thread/thread/a3f12d578f5a2619)

您可以在包含父 ID 的 before_destroy 中设置一些实例变量，然后在 after_destroy 回调中根据此 ID 进行查找并决定是否删除那里的父母基于计算孩子

You could set some instance variable in before_destroy containing the parent's ID, then do a lookup based on this id in an after_destroy callback and decide whether to delete the parent there based on counting the children

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