code: def save_callback(sender, instance, created, update_fields, **kwargs):
      
      if validate_instance(instance):
          status = 'add' if created is True else 'change'
          change = ''
  
          if status == 'change' and 'al_chl' in instance.__dict__.keys():
              changelog = instance.al_chl.modification
              change = ' to following changed: {}'.format(changelog)
  
          processor(status, sender, instance, update_fields, addition=change)
docs: Save object & link logging entry