保存期间视图集中模型的自动递增字段

Question

视频集模型具有Episode_number字段，在创建新的视频集时必须自动将其递增。每个故事都有情节，这些情节的episod_number字段以一个开头。怎么做？现在，我用户必须手动输入Episode_number。 story_id来自网址

class Story(models.Model):
    title = models.CharField(max_length=255)
    description = models.TextField(max_length=255)
    cover = models.ImageField(upload_to=upload_location)
    genre = models.ManyToManyField(Genre)
    author = models.ForeignKey(get_user_model(), on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)

class Episode(models.Model):
    title = models.CharField(max_length=255)
    cover = models.ImageField(upload_to=upload_location)
    story = models.ForeignKey(Story, on_delete=models.CASCADE)
    created_at = models.DateTimeField(auto_now_add=True)
    episode_number = models.IntegerField(null=True)

class EpisodeView(viewsets.ModelViewSet):
    serializer_class = EpisodeSerializer
    permission_classes = [BasicAuthorizationPermissions]

    def get_queryset(self):
        story_id = self.kwargs['story_id']
        return Episode.objects.filter(story=story_id)

    def perform_create(self, serializer):
        try:
            story = Story.objects.get(pk=self.kwargs['story_id'])
        except Story.DoesNotExist:
            raise NotFound

        if self.request.user != story.author:
            raise PermissionDenied

        return serializer.save(story=story)

Answer 1

案例情况

当基于参考Episod模型Story的{​​{1}}模型中有新条目时，应自动填充。

可能的解决方案

我们将覆盖episode_number模型的默认保存方法，并检查这是否是新实例的条目，我们将从此处设置其值。

Episod