将列表传递给 APIVIew 中的 Manytomany 字段，出现错误“类型不正确。预期的 pk 值，已收到 str。”

Question

我创建了 API 来创建更新案例但问题在于 task 如果我在通过邮递员更新或创建时只传递一个 pk like(task=1) 那么它工作正常并且案例将通过引用该任务来创建但是一个任务是一个多态字段我需要将多个任务pk分配给task = [1,2]这样的案例然后它会给出像

这样的错误

        "Incorrect type. Expected pk value, received str."
    ]

class Case(models.Model):
    name = models.CharField(max_length=200)
    task = models.ManyToManyField('task.Task',blank=True, null=True)
    assigned_to = models.ForeignKey("account.User",null=True, blank=True, on_delete=models.SET_NULL)

class CaseSerializer(serializers.ModelSerializer):
    class Meta:
        model = Case
        fields = ('id', 'name', 'task', 'assigned_to')
class CaseCreateView(APIView):
    permission_classes = (IsAuthenticated,)

    @access_permission('case_create')
    def post(self, request, format=None):
        serializer = CaseSerializer(data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)


class CaseUpdateView(APIView):
    permission_classes = (IsAuthenticated,)
    model = Case

    @access_permission('case_edit')
    def put(self, request,pk, format=None):
        case = get_object(self,pk)
        serializer = CaseSerializer(case,data=request.data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

Answer 1

我也是 DRF 的新手，大部分时间我只是使用Generic，但我会尝试帮助你。在您的序列化程序中添加read_only_fields=(task, )，然后我们将手动将tasks 添加到Case 实例。通过这种方式在创建方法中我们不需要“任务”并且序列化程序将有效。 序列化器.py：

class CaseSerializer(serializers.ModelSerializer):
    class Meta:
        model = Case
        fields = ('id', 'name', 'task', 'assigned_to')
        read_only_fields = ('task', )

class CaseUpdateView(APIView):
    permission_classes = (IsAuthenticated,)
    model = Case

    @access_permission('case_edit')
    def put(self, request,pk, format=None):
        case = get_object(self,pk)
        serializer = CaseSerializer(case,data=request.data)
        if serializer.is_valid():
            serializer.save()
            task_id_list = request.data['tasks_id'] # depending on request
            for task_id in task_id_list: # this way we can add to M2M field manually  
                  task = Task.object.get(id=task_id)
                  case.task.add(task)
            return Response(serializer.data, status=status.HTTP_201_CREATED)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)