code: def update_post_relations(user, topic, deleting=False):
      
      if deleting:
          user.post_count = user.post_count - 1
      else:
          user.post_count += 1
      user.save(update_fields=['post_count'])
  
      topic.modified     = datetime.now()
      topic.modified_int = time.time()
      topic.save(update_fields=['modified', 'modified_int'])
docs: helper function to update user post count and parent topic post_count.