我试图返回某个用户的朋友的所有朋友，该用户是该关系的作者。
但是，我不断收到此错误：
验证位于/author/posts的错误[""[UUID（'8 c 02 a503 -7784- 42 f0-a367- 1876 bbfad 6 ff'）]”不是有效的UUID。"]

class Author(AbstractUser):
    ...
    uuid = models.UUIDField(primary_key=True, default=uuid4, editable=False, unique=True)
    ...

class Post(models.Model):
    ...
    author = models.ForeignKey(Author, on_delete=models.CASCADE)
    ...

class Friend(models.Model):
    class Meta:
        unique_together = (('author','friend'),)
    author = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='author')
    friend = models.ForeignKey(Author, on_delete=models.CASCADE, related_name='friend')

特别是foaf行是错误的来源。我还能怎么做呢？

friends = Friend.objects.filter(author=userUUID)
foafs = Friend.objects.filter(friend=[friend.friend.uuid for friend in friends])