code: def _create_update_tracking_event(instance):
      
      event = _create_event(instance, UPDATE)
      for field in instance._tracked_fields:
          if not isinstance(instance._meta.get_field(field), ManyToManyField):
              try:
                  if isinstance(instance._meta.get_field(field), ForeignKey):
                      # Compare pk
                      value = getattr(instance, '{0}_id'.format(field))
                  else:
                      value = getattr(instance, field)
                  if instance._original_fields[field] != value:
                      _create_tracked_field(event, instance, field)
              except TypeError:
                  # Can't compare old and new value, should be different.
                  _create_tracked_field(event, instance, field)
docs: Create a TrackingEvent and TrackedFieldModification for an UPDATE event.