django：更改父母，当孩子被删除时（单向OneToone）

Question

当我删除标记为photphoto对象时，我想更改照片“标记”字段false。

#models.py
class Photo(models.Model):
    image = models.ImageField(upload_to='shoes_data/%Y/%m/%d', name='image')
    created = models.DateTimeField(auto_now_add=True)
    labeled = models.BooleanField(default=False)

class LabeledPhoto(models.Model):
    labeled_image = models.OneToOneField(Photo, on_delete=models.PROTECT, related_name='labeled_image')
    topcategory = models.CharField(max_length=64)
    subcategory = models.CharField(max_length=64)
    labeler = models.CharField(max_length=32)
    created = models.DateTimeField(auto_now_add=True)
    updated = models.DateTimeField(auto_now=True)

我尝试过这样的

# views.py
class LabeledPhotoDelete(DeleteView):
    model = LabeledPhoto
    template_name = 'label/labeled_photo_delete.html'
    success_url = reverse_lazy('photo:labeled_list')

    def delete(self, request, *args, **kwargs):
        self.object = self.get_object()
        success_url = self.get_success_url()
        labeled = LabeledPhoto.objects.get(id=self.object.pk)
        labeled.labeled_image.labeled = False
        labeled.save()
        self.object.delete()
        return reverse(success_url)

Answer 1

您需要.save（） photo：

from django.http import HttpResponseRedirect

class LabeledPhotoDelete(DeleteView):
    model = LabeledPhoto
    template_name = 'label/labeled_photo_delete.html'
    success_url = reverse_lazy('photo:labeled_list')

    def delete(self, request, *args, **kwargs):
        self.object = self.get_object()
        success_url = self.get_success_url()
        image = self.object.labeled_image
        image.labeled = False
        image.save()
        self.object.delete()
        return HttpResponseRedirect(success_url)

但是没有理由存储是否在字段中标记图像：知道这一点。实际上，您可以添加一个属性：

class Photo(models.Model):
    image = models.ImageField(upload_to='shoes_data/%Y/%m/%d', name='image')
    created = models.DateTimeField(auto_now_add=True)

    @property
    def labeled(self):
        try:
            return self.labeled_image is not None
        except LabeledPhoto.DoesNotExist:
            return False

如果存在labeledphoto的事实，则将QuerySet注释：

from django.db.models import BooleanField, ExpressionWrapper, Q

Photo.objects.annotate(
    is_labeled=ExpressionWrapper(
        Q(labeled_image__isnull=False),
        output_field=BooleanField()
    )
)