error_messages_for

 在http://www.ruby-forum.com/topic/114652#new论坛中看到如下问题：

   I have a database table called "hvd_codes", the model is called HvdCode.
In my form partial, what should I enter as a parameter to
error_messages_for? I've tried <%= error_messages_for 'hvd_codes' %> but nothing is
displayed.
   IRC error_messages_for simply looks for a global variable named after
its parameter and parse the result 'errors' called on it.
So if you have a @hvdcode which is a HvdCode instance, just use
'hvdcode'. If you had a @foo instance of HvdCode, you'd use  'foo'...