在 django 中，如何限制我们可以通过有条件和无条件保存的对象数量？

Question

意思是，我只想保存一个 object 且 is_featured 字段为 true，如果用户尝试保存另一个 object 且 is_featured 字段为 true，则需要提示，我该如何在 Z2B9AFB89A6ACC1575B159BFCA38D 中实现这一点？

class Event(BaseModel):
    title = models.CharField(max_length=200)
    time = models.TimeField()
    date = models.DateField()
    location = models.CharField(max_length=200)
    location_url = models.URLField()
    description = models.TextField()
    is_featured = models.BooleanField(default=False)
    image = VersatileImageField('Image', upload_to="web/events")

    class Meta:
        db_table = 'web_event'
        verbose_name = ('Event')
        verbose_name_plural = ('Event')
        ordering = ('auto_id',)

    def __str__(self):
        return str(self.title)

Answer 1

您可以添加检查是否已使用 is_featured true 创建了事件，那么您可以返回错误，否则您可以创建实例

if Event.objects.filter(is_featured=True).exists():
   return Response({"error":"Featured Event Already Exists"})
else:
   Event.objects.create(**data)
```