我在 Django REST Framework view.py 中修改 response.data。为什么我在测试期间收到 AttributeError 而不是实际 API 使用？

Question

我的 Django REST Framework API 工作正常。在 view.py 中，我修改了 OrderViewSet，def partial_update，在将 response.data 字典保存到数据库之前将另一个 key/value 对添加到它。当我用 Postman 调用 API 时，它可以正常工作。

但是，当我运行测试相同的功能时，它失败了并且 returns:

request.data["submission_date"] = datetime.now()
AttributeError: This QueryDict instance is immutable

如果在实际 API 使用期间未发生此错误，为什么我会在测试期间收到此错误？

View.py

class OrderViewSet(viewsets.ModelViewSet):
    """ Includes custom PATCH functionality """
    queryset = Order.objects.all().order_by('-order_date')
    serializer_class = OrderSerializer
    authentication_classes = (authentication.TokenAuthentication,)
    permission_classes = [permissions.IsAuthenticated]

    def partial_update(self, request, *args, **kwargs):
        """ Update status and timestamp fields accordingly """
        status = request.data['status']

        if status == 'submitted':
            request.data["submission_date"] = datetime.now()

        if status == 'packaged':
            request.data["packaged_date"] = datetime.now()

        if status in ['sold', 'canceled', 'abandoned']:
            request.data["finished_date"] = datetime.now()

        return super().partial_update(request, *args, **kwargs)

Test.py

def test_patch_order_status_from_cart_to_submitted(self):
    """ test patching order status from cart to submitted """
    order = sample_order(user=self.user)

    payload = {
        "status": "submitted"
    }

    res = self.client.patch(order_detail_url(order.id), payload)
    self.assertEqual(res.status_code, status.HTTP_200_OK)

    patched_order = Order.objects.get(id=order.id)
    self.assertEqual(patched_order.status, 'submitted')

def test_submitted_timestamp(self):
    """ test that patching order status to submitted also leaves timestamp """
    order = sample_order(user=self.user)

    payload = {
        "status": "submitted"
    }

    self.client.patch(order_detail_url(order.id), payload)

    patched_order = Order.objects.get(id=order.id)
    self.assertNotEqual(patched_order.submission_date, None)

编辑：

如果我要像下面那样修改 request.data 的副本，我怎么能从函数中 return 它呢？

    def partial_update(self, request, *args, **kwargs):
    """ Update status and timestamp accordingly """
    modified_data = request.data.copy()
    status = request.data['status']

    if status == 'submitted':
        modified_data["submission_date"] = datetime.now()

    if status == 'packaged':
        modified_data["packaged_date"] = datetime.now()

    if status in ['sold', 'canceled', 'abandoned']:
        modified_data["finished_date"] = datetime.now()

    return super().partial_update(request, *args, **kwargs)

解决方案：现在测试通过了。

views.py:

    ...

    def partial_update(self, request, pk, *args, **kwargs):
        """ Update status and timestamp accordingly """
        order = Order.objects.get(id=pk)
        serializer = OrderSerializer(order, data=request.data, partial=True)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data)
        else:
            return Response(serializer.errors)

Serializers.py:

class OrderSerializer(serializers.ModelSerializer):

    def update(self, order, validated_data):
        """ Update status and timestamp accordingly """
        status = validated_data.get('status')
        order.status = status
        if status == 'submitted':
            order.submission_date = datetime.now()
        elif status == 'packaged':
            order.packaged_date = datetime.now()
        elif status in ['sold', 'canceled', 'abandoned']:
            order.finished_date = datetime.now()

        order.save()
        return order

    class Meta:
        model = Order
        fields = '__all__'
        read_only_fields = ('id', 'user')

Answer 1

你是说修改request.data？我之前也遇到过这个错误。

然后我看了Django documentation QueryDict，我觉得“request.data”：

是dictionary-like，不是字典。
数据类型不可变。

修改前复制，如：

 req_data = request.data.copy()
 req_data['submission_date'] = datetime.now()

而在实际API使用过程中没有发生错误的原因，可能只是状态不在这些情况下。

另一方面，在这种情况下，我通常在models.py中设置一个modified_at或created_at DateTimeField，这样会记录submission_date每当修改或创建数据时自动。我觉得方便。

created_at = models.DateTimeField(auto_now_add=True, help_text="submission_date")
modified_at = models.DateTimeField(auto_now=True, help_text="re-submission_date")

编辑使用 ModelSerializer 寻找另一种可能的解决方案：

目的：我们要更新的数据不只是直接基于request.data。我们想使用一些其他的逻辑：if status == 'submitted' then...

我想 submission_date、packaged_date、finished_date 是订单模型的字段。

views.py

def partial_update(self, request, pk, *args, **kwargs):
    order = Order.objects.get(id=pk)
    serializer = OrderSerializer(order, data=request.data, partial=True)
    if serializer.is_valid():
        serializer.save()
        return Response(serializer.data)
    else:
        return Response(serializer.errors)

serializers.py

class OrderSerializer(serializers.ModelSerializer):
    class Meta:
        model = Order
        fields = '__all__'

    def update(self, order, validated_data):
        status = validated_data.get('status')
        order.status = status
        if status == 'submitted':
            order.submission_date = datetime.now()
        elif status == 'packaged':
            order.packaged_date = datetime.now()
        elif status in ['sold', 'canceled', 'abandoned']:
            order.finished_date = datetime.now()

        order.save()
        return order

我在 Django REST Framework view.py 中修改 response.data。为什么我在测试期间收到 AttributeError 而不是实际 API 使用？

I modify response.data in Django REST Framework view.py. Why am I getting an AttributeError during testing but not with actual API use?

python

django

rest

unit-testing

frameworks

解决方案：现在测试通过了。