如何引发错误/返回{“ foo”：[“此字段为必填。”]}在Django REST中的响应

Question

假设我有一个视图，我需要在调用serializer.save之前检查是否已给出字段，以确保我没有字典键错误：

class BarView(CreateAPIView):
    serializer_class = BarSerializer
    queryset = Bar.objects.all()
    def perform_create(self, serializer):
        if 'foo' not in self.request.data:
            raise ParseError('foo field required.')
        foo = get_object_or_404(Foo, pk=self.request.data['foo'])
        if foo.counter == 10:
            raise ParseError('foo limit reached.')
        return serializer.save(user=self.request.user, foo=foo)

而不是返回"foo field required."，我想返回的消息与Django REST返回的消息相同，例如{"foo":["This field is required."]}

有更好的方法吗？也许仅通过序列化程序验证foo字段？

更新：我忘记提及用户字段也是必需的。

Bar的模型是：

class Bar(models.Model):
    user = models.ForeignKey(User, db_index=True, editable=False)
    foo = models.ForeignKey(Foo, db_index=True)

Answer 1

是，

仅查看文档：Validation

（

[我假设字段foo是Bar模型的一部分，如果不是，请在fields中将其添加到Meta中）：向BarSerializer添加验证：

class BarSerializer(serializers.ModelSerializer):
    def validate_foo(self, value):
        if not value:
            raise serializers.ValidationError("foo field required.")
        if Foo.objects.filter(pk=value, counter__gte=10).exists():
            raise serializers.ValidationError("foo limit reached.")
        return value

    class Meta:
        model = Bar

然后通过扩展此内容来创建您的视图：

from rest_framework.exceptions import ValidationError

class MyCreateAPIView(CreateAPIView):        
    def post(self, request, *args, **kwargs):
        try:
             return super(BarView, self).post(request, *args, **kwargs)
        except ValidationError as e:
             return Response(e.detail, , status=status.HTTP_400_BAD_REQUEST)

    def create(self,request, *args, **kwargs):
        serializer = self.get_serializer(data=request.data)
        serializer.is_valid(raise_exception=True)
        try:
            self.perform_create(serializer)       
        except DjangoValidationError as e:
            raise ValidationError(e.messages)
        self.perform_create(serializer)
        headers = self.get_success_headers(serializer.data)
        return Response(serializer.data, status=status.HTTP_201_CREATED, headers=headers)

    def perform_create(serializer):
        # do your stuff
        serializer.save()

Answer 2

是，执行此操作的最佳方法是使用foo类中的extra_kwargs选项，在序列化程序中创建extra_kwargs字段。

Answer 3

您可以使用用户定义的消息返回

class BarView(CreateAPIView):
    serializer_class = BarSerializer
    queryset = Bar.objects.all()

    def perform_create(self, serializer):
        return serializer.save(user=self.request.user, foo=serializer.foo_object)