ruby-on-rails - rails :dependent => :destroy VS :dependent => :delete_all

Question

在rails guides中是这样描述的:

Objects will be in addition destroyed if they’re associated with :dependent => :destroy, and deleted if they’re associated with :dependent => :delete_all

好的，很酷。但是被销毁和被删除有什么区别呢？ 我都试过了，它似乎做同样的事情。

Answer 1

区别在于回调。

:delete_all 直接在您的应用程序中创建并通过 SQL 删除:

DELETE * FROM users where compagny_id = XXXX

通过 :destroy，您的所有 child 都有一个实例化。所以，如果你不能销毁它或者如果每个都有自己的 :dependent，它的回调可以被调用。