如何使用 django-rest-framework 保存外键

Question

我是 Django 的新手，我正在尝试将 Unit 和 current_user 外键保存在数据库中基于获得的 pk 但是每次我尝试这样做但是运行分为两种类型错误 serializers.is_valid() 引发异常错误或序列化程序 returns "Invalid data. Expected a dictionary, but got Unit."

我尝试了一种非常非常丑陋的方法来绕过序列化程序，但我得到了 ee8452a4-2a82-4804-a010-cf2f5a41e006 must be an instance of SavedUnit.unit.I 我也尝试过直接使用保存外键SavedUnit.objects.create()运气不好

model.py

class SavedUnit(models.Model):
    """
    Saving units for later models
    relationship with units and users
    """
    id = models.UUIDField(primary_key=True, default=hex_uuid, editable=False)
    unit = models.ForeignKey(Unit, on_delete=models.CASCADE)
    user = models.ForeignKey('accounts.User', on_delete=models.CASCADE, related_name='user')
    published_at = models.DateTimeField(auto_now_add=True)

serializers.py

class SavedSerializer(serializers.ModelSerializer):
    unit = UnitSerializer()
    class Meta:
        model = SavedUnit
        fields = [
            'id',
            'unit'
        ]

views.py

class SavedUnitView(APIView):
    """
    Query all the unites saved
    """
    @staticmethod
    def get_unit(request, pk):
        try:
            return Unit.objects.get(pk=pk)
        except Unit.DoesNotExist:
            return Response(status=status.HTTP_400_BAD_REQUEST)
    @staticmethod
    def post(request, pk):
        if request.user.is_authenticated:
            unit = get_object_or_404(Unit, id=pk)
            serializers = SavedSerializer(data=unit)
            if serializers.is_valid(raise_exception=True):
                created = SavedUnit.objects.get_or_create(
                    user=request.user,
                    unit=unit)
                return Response(status=status.HTTP_201_CREATED)
        return Response(status=status.HTTP_401_UNAUTHORIZED)
    def get(self, request):
        units = SavedUnit.objects.filter(user=self.request.user.id)
        try:
            serializers = SavedSerializer(units, many=True)
            return Response(serializers.data, status=status.HTTP_200_OK)
        except Unit.DoesNotExist:
            return Response(status=status.HTTP_500_INTERNAL_SERVER_ERROR)

Answer 1

其实问题出在这里：

def post(request, pk):
    if request.user.is_authenticated:
        unit = get_object_or_404(Unit, id=pk)
        serializers = SavedSerializer(data=unit)  <-- Here

您正在传递一个单元实例，但它应该是 request.data，如下所示：

serializers = SavedSerializer(data=request.data)

( 我不确定你在做什么，如果你已经有了 PK，那你为什么还要使用序列化器？因为你不需要它，因为你已经有了这个单元，你可以从访问当前用户request.user，你已经在做了。而且我认为你不应该使用 @staticmethod，你可以这样声明 post 方法：def post(self, request, pk) 并删除静态方法装饰器)

Answer 2

您的代码仅使用序列化程序进行验证，但可以使用它在数据库调用时插入或更新新对象 serializer.save()。

要使用django-rest-framework 保存外键，您必须在序列化器上放置一个相关字段来处理它。使用 PrimaryKeyRelatedField。

serializers.py

class SavedSerializer(serializers.ModelSerializer):
    unit_id = serializers.PrimaryKeyRelatedField(
        source='unit',
        queryset=Unit.objects.all()
    )
    unit = UnitSerializer(read_only=True)

    class Meta:
        model = SavedUnit
        fields = [
            'id',
            'unit_id',
            'unit'
        ]

views.py

class SavedUnitView(APIView):
    permission_classes = (permissions.IsAuthenticated,) # For not handling authorization mannually

    def post(request):
        serializer = SavedSerializer(data=request.data)
        serializer.is_valid(raise_exception=True)  # Trigger Bad Request if errors exist
        serializer.save(user=request.user)         # Passing the current user
        return Response(serializer.data, status=status.HTTP_201_CREATED)

现在，单元的id将像这样在请求体中传递

POST /saved-units/
Accept: application/json
Content-Type: application/json
Authorization: Token your-api-token

{ 
    "unit_id": 5  # Id of an existing Unit
}

如何使用 django-rest-framework 保存外键

how to save foreign keys using django-rest-framework

django

python-3.x

django-rest-framework

django-2.1