相关模型属性的Django唯一约束

def BookModel(TimeStampedModel):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    bookname = models.CharField()

    class Meta:
        constraints = [
            models.UniqueConstraint(fields=['user ', 'bookname'],
                                    name='StackOverflow.Question')
        ]

每个用户只能有一个 BookModel 用一个特定的 bookname .

不过,现在我想介绍一下 LibraryModel

class LibraryModel(TimeStampedModel):
    user = models.ForeignKey(User, on_delete=models.CASCADE)
    name = models.CharField(max_length=32)


def BookModel(TimeStampedModel):

    library = models.ForeignKey(LibraryModel, on_delete=models.CASCADE)
    bookname = models.CharField()

    class Meta:
        constraints = [
            models.UniqueConstraint(fields=['library_user', 'bookname'],
                                    name='StackOverflow.Question')
        ]

当我运行migrate时,它说 django.core.exceptions.FieldDoesNotExist: BookModelhas no field named 'library_user' .

fields=['library__user' 和 fields=['library.user' ,无济于事。

这有可能吗?或者我应该把 user