Rails: around_* callbacks

问题:

I have read the documentation at http://api.rubyonrails.org/classes/ActiveRecord/Callbacks.html, but don't understand when the around_* callbacks are triggered in relation to before_* and after_*.

Any help much appreciated.

Thanks.

回答1:

around_* callbacks are invoked before the action, then when you want to invoke the action itself, you yield to it, then continue execution. That's why it's called around

The order goes like this: before, around, after.

So, a typical around_save would look like this:

def around_save    #do something...    yield #saves    #do something else... end 

回答2:

The around_* callback is called around the action and inside the before_* and after_* actions. For example:

class User   def before_save     puts 'before save'   end    def after_save     puts 'after_save'   end    def around_save     puts 'in around save'     yield # User saved     puts 'out around save'   end end  User.save   before save   in around save   out around save   after_save => true 

文章来源: Rails: around_* callbacks