Compare old and updated fields in Django model

Question

I want to compare old and updated field in model. I have did this issue for one field but i want do this for all fields:

class MyUser(User)
    def save(self, **kwargs):
       if self.pk is not None:
         orig = MyUser.objects.get(pk=self.pk)
         orig_field_names = orig._meta.get_all_field_names()
         field_names = self._meta.get_all_field_names()
         # I want do this in loop 
         if orig.first_name != self.first_name:
           print 'first_name changed'
           UpdateLog.objects.create(
                user = orig,
                filed_name = self.first_name,
                update_time = datetime.now()
             )
         super(MyUser, self).save(**kwargs)

Thanks in advance

Answer 1

You want a signal. For quick reference, here's the introductory paragraph or so from that link:

Django includes a “signal dispatcher” which helps decoupled applications get notified when actions occur elsewhere in the framework. In a nutshell, signals allow certain senders to notify a set of receivers that some action has taken place. They’re especially useful when many pieces of code may be interested in the same events.

Django provides a set of built-in signals that let user code get notified by Django itself of certain actions.

Answer 2

Read the docs before vote -1. Catch the signal is the better way to do this thing