Python 在模型save django上从多到多字段命名一个文件

我想根据其他模型字段（特别是多对多字段）保存具有特定名称的图像。当我尝试访问标记post_save（或son save（））时会出现问题，该标记不提供任何标记

def path_to_upload(instance, filename):
  ext = filename.split('.')[-1]
  if instance.category:
    upload_to = 'images/' + instance.category.category_dir
    filename = 'Meme-{}-{}.{}'.format(instance.category.title, uuid4().hex, ext)
  else:
    upload_to = 'images/uncategorized/'
    filename = 'Meme-{}-{}.{}'.format('uncategorized', uuid4().hex, ext)
  return os.path.join(upload_to, filename)

class Meme(models.Model):
  title = models.CharField(max_length=1024, default='')
  category = models.ForeignKey(Category, null=True, on_delete=models.PROTECT)
  tags = TaggableManager()
  image = models.ImageField(upload_to=path_to_upload, default='')
  image_thumbnail = ImageSpecField(source='image', processors=[ResizeToFill(350, 200)], format='JPEG', options={'quality': 50})
  slug = models.SlugField(max_length=355, blank=True, default='')



def save_meme(sender, instance, **kwargs):
  print(instance.tags.all())

post_save.connect(save_meme, sender=Meme)

打印时，它会给我空的查询集