python - 如何在 django-mptt 中修复没有 child 的 parent ？

Question

我想为每个 parent 修复 2 个 child 。
模型.py

class CoachingRegistration(MPTTModel):
    uid = models.UUIDField(unique=True, editable=False, default=uuid.uuid4)
    placement_id = models.CharField(max_length=13)

    parent = TreeForeignKey('self', on_delete=models.CASCADE, null=True, blank=True, related_name='children')

    class MPTTMeta:
        order_insertion_by = ['placement_id']

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

请帮我解决这个问题。

Answer 1

您可以使用 form_valid 函数在 createview 中修复此问题

class CoachingRegistrationCreate(LoginRequiredMixin, SuccessMessageMixin, CreateView):
    model = CoachingRegistration
    form_class = CoachingRegistrationForm
    template_name = 'customer/form_coaching_register.html'

    def form_valid(self, form):
        if 2 > CoachingRegistration.objects.filter(parent=CoachingRegistration.objects.get(coaching_id=form.instance.placement_id)).count():
            return super().form_valid(form)
        else:
            return super().form_invalid(form)