python - Django 条件唯一在一起

Question

我有一个如下所示的模型:

class LibraryEntry(models.Model):
  host_lib_song_id = models.IntegerField()
  song = models.CharField(max_length=200)
  artist = models.CharField(max_length=200)
  album = models.CharField(max_length=200)
  owning_user = models.ForeignKey(User)
  is_deleted = models.BooleanField(default=False)

现在，如果我选择 where is_deleted=False，host_lib_song_id 和 owning_user 的组合应该是唯一的。我该如何表达呢？

Answer 1

覆盖 validate_unique如果 is_deleted 为 False 则检查唯一性更合适:

...

def validate_unique(self, exclude=None):
    if not self.is_deleted and \
       LibraryEntry.objects.exclude(pk=self.pk).filter(host_lib_song_id=self.host_lib_song_id, owning_user=self.owning_user).exists():
        raise ValidationError('Some error message about uniqueness required')
    super(LibraryEntry, self).validate_unique(exclude=exclude)