Django rest 框架，在序列化程序中创建用户字段时出错

Question

I have an API that didn't contain a created by user field.

I decided to add such field in the serializer:

class PointsSerializer(PermissionRequiredMixin, HyperlinkedModelSerializer):
    date_added = DateTimeField(format="%d-%m-%Y", required=False, read_only=True)
    created_by = serializers.CharField(default=CurrentUserDefault(),)

    class Meta:
        model = Points
        fields = (
            'created_by', 'MissionName', 'location_name', 'GDT1Latitude', 'GDT1Longitude',
            'UavLatitude', 'UavLongitude', 'UavElevation', 'Area',
            'date_added'
        )

until now my logic in the view worked fine, after migrating to this changes I started getting this error in the view when trying to serialize data and use it:

class PointsViewSet(ModelViewSet):
    # Return all order by id, reversed.
    queryset = Points.objects.all().order_by('-id')
    serializer_class = PointsSerializer
    data = queryset[0]
    serialized_data = PointsSerializer(data, many=False)
    pprint(serialized_data)
    points = list(serialized_data.data.values())

    search_fields = ['MissionName', 'date_added']
    ordering_fields = ['id', 'MissionName', 'Area', 'date_added']
    filter_backends = (filters.SearchFilter, filters.OrderingFilter)

    @action(detail=True, methods=["post"])
    def last_object_by_user(self, request, *args, **kwargs):
        # your query to get the last object by your user
        queryset = Points.objects.filter(created_by=request.user).latest()
        return queryset

    def retrieve(self, request, *args, **kwargs):
        """
        Main Triangulation Logic.
        This method takes in all the parameters posted by the user and returns the mission generated map.
        :rtype: Mission File Object 
        """
        mission_name = self.points[1]
        mission_reference = f'{DIR}/{mission_name}.{HTML}'

        assign_gdt = GeoPoint(lat=self.points[2], long=self.points[3])
        gdt1 = [assign_gdt.get_lat(), assign_gdt.get_long()]

        assign_uav = GeoPoint(lat=self.points[4], long=self.points[5], elevation=self.points[6])
        uav = [assign_uav.get_lat(), assign_uav.get_long(), assign_uav.get_elevation()]

        area_name = f"'{self.points[-3]}'".capitalize()

        if not request.user.is_authenticated:
            return HTTP_401_UNAUTHORIZED
        try:

            return render(request, mission_reference), print("Mission file already existed")
        except:
            main = MainApp.run(gdt1=gdt1, uav=uav, mission_name=mission_name, area=area_name)
            return render(request, main), print('New mission file was created')

the error being raised on point variable:

Exception in thread django-main-thread:
Traceback (most recent call last):
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/fields.py", line 454, in get_attribute
    return get_attribute(instance, self.source_attrs)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/fields.py", line 94, in get_attribute
    instance = getattr(instance, attr)
AttributeError: 'Points' object has no attribute 'created_by'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/usr/lib/python3.7/threading.py", line 926, in _bootstrap_inner
    self.run()
  File "/usr/lib/python3.7/threading.py", line 870, in run
    self._target(*self._args, **self._kwargs)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/utils/autoreload.py", line 53, in wrapper
    fn(*args, **kwargs)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/core/management/commands/runserver.py", line 117, in inner_run
    self.check(display_num_errors=True)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/core/management/base.py", line 395, in check
    include_deployment_checks=include_deployment_checks,
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/core/management/base.py", line 382, in _run_checks
    return checks.run_checks(**kwargs)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/core/checks/registry.py", line 72, in run_checks
    new_errors = check(app_configs=app_configs)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/core/checks/urls.py", line 13, in check_url_config
    return check_resolver(resolver)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/core/checks/urls.py", line 23, in check_resolver
    return check_method()
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/urls/resolvers.py", line 407, in check
    for pattern in self.url_patterns:
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/urls/resolvers.py", line 588, in url_patterns
    patterns = getattr(self.urlconf_module, "urlpatterns", self.urlconf_module)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/utils/functional.py", line 48, in __get__
    res = instance.__dict__[self.name] = self.func(instance)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/urls/resolvers.py", line 581, in urlconf_module
    return import_module(self.urlconf_name)
  File "/usr/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/yovel/PycharmProjects/Triangulation/triangulationapi/triangulationapi/urls.py", line 25, in <module>
    path('', include('find_second_gdt.urls')),
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/django/urls/conf.py", line 34, in include
    urlconf_module = import_module(urlconf_module)
  File "/usr/lib/python3.7/importlib/__init__.py", line 127, in import_module
    return _bootstrap._gcd_import(name[level:], package, level)
  File "<frozen importlib._bootstrap>", line 1006, in _gcd_import
  File "<frozen importlib._bootstrap>", line 983, in _find_and_load
  File "<frozen importlib._bootstrap>", line 967, in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 677, in _load_unlocked
  File "<frozen importlib._bootstrap_external>", line 728, in exec_module
  File "<frozen importlib._bootstrap>", line 219, in _call_with_frames_removed
  File "/home/yovel/PycharmProjects/Triangulation/triangulationapi/find_second_gdt/urls.py", line 4, in <module>
    from .views import PointsViewSet
  File "/home/yovel/PycharmProjects/Triangulation/triangulationapi/find_second_gdt/views.py", line 18, in <module>
    class PointsViewSet(ModelViewSet):
  File "/home/yovel/PycharmProjects/Triangulation/triangulationapi/find_second_gdt/views.py", line 24, in PointsViewSet
    points = list(serialized_data.data.values())
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/serializers.py", line 562, in data
    ret = super().data
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/serializers.py", line 260, in data
    self._data = self.to_representation(self.instance)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/serializers.py", line 516, in to_representation
    attribute = field.get_attribute(instance)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/fields.py", line 469, in get_attribute
    return self.get_default()
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/fields.py", line 513, in get_default
    return self.default(self)
  File "/home/yovel/PycharmProjects/Triangulation/ven/lib/python3.7/site-packages/rest_framework/fields.py", line 287, in __call__
    return serializer_field.context['request'].user
KeyError: 'request'

Answer 1

Remove the following class members from PointsViewSet . Your serializer now requires the request in the context when instantiating it, but this can't supply it as it gets run when the class is imported.

data = queryset[0]
serialized_data = PointsSerializer(data, many=False)
pprint(serialized_data)
points = list(serialized_data.data.values())

Answer 2

as @ schilling stated, what I didn't understand is that I should return points in a method.

So, This is the new view:

class PointsViewSet(ModelViewSet):
    # Return all order by id, reversed.
    def get_queryset(self):
        queryset = Points.objects.all().order_by('-id')
        return queryset

    def get_serializer_class(self):
        return PointsSerializer

    search_fields = ['MissionName', 'date_added']
    ordering_fields = ['id', 'MissionName', 'Area', 'date_added']
    filter_backends = (filters.SearchFilter, filters.OrderingFilter)

    def get_object(self):
        queryset = self.get_queryset()
        data = queryset[0]
        serialized_data = PointsSerializer(data, many=False)
        points = list(serialized_data.data.values())
        return points

    @action(detail=True, methods=["post"])
    def last_object_by_user(self, request, *args, **kwargs):

        queryset = Points.objects.filter(created_by=request.user).latest()
        return queryset

    # @action(detail=True, methods=["post"])
    def retrieve(self, request, *args, **kwargs):
        """
        Main Triangulation Logic.
        This method takes in all the parameters posted by the user and returns the mission generated map.
        :rtype: Mission File Object
        """
        points = self.get_object()
        mission_name = points[1]
        mission_reference = f'{DIR}/{mission_name}.{HTML}'

        assign_gdt = GeoPoint(lat=points[2], long=points[3])
        gdt1 = [assign_gdt.get_lat(), assign_gdt.get_long()]

        assign_uav = GeoPoint(lat=points[4], long=points[5], elevation=points[6])
        uav = [assign_uav.get_lat(), assign_uav.get_long(), assign_uav.get_elevation()]

        area_name = f"'{points[-3]}'".capitalize()

        if not request.user.is_authenticated:
            return HTTP_401_UNAUTHORIZED
        try:

            return render(request, mission_reference), print("Mission file already existed")
        except:
            main = MainApp.run(gdt1=gdt1, uav=uav, mission_name=mission_name, area=area_name)
            return render(request, main), print('New mission file was created')