Django 序列化器定义初始对象

Question

我似乎无法弄清楚如何将初始值传递给序列化程序。我有一个多租户 django 站点，现在我正在尝试设置 API。客户字段存在，但需要隐藏和只读。我认为这就像传统 django 中的一种形式和一种视图。我通常会在视图中传入 get_initial 。我先尝试过，但它不起作用。我想我需要直接在序列化程序中获取值，但我似乎无法让它工作。

型号：

class Location(ClientAwareModel):
    name = models.CharField(max_length=64, blank=True)
    address = models.CharField(max_length=64)
    address2 = models.CharField(max_length=64, blank=True)
    city = models.CharField(max_length=64)
    state = USStateField()
    zip_code = USZipCodeField()

class Client(models.Model):
    name = models.CharField(max_length=100)
    subdomain_prefix = models.CharField(max_length=100, unique=True)

    def __str__(self):
        return self.name

class ClientAwareModel(models.Model):
    client = models.ForeignKey(Client, on_delete=models.PROTECT)

    class Meta:
        abstract = True

def hostname_from_request(request):
    # split on `:` to remove port
    return request.get_host().split(':')[0].lower()

def client_from_request(request):
    hostname = hostname_from_request(request)
    subdomain_prefix = hostname.split('.')[0]
    return Client.objects.filter(subdomain_prefix=subdomain_prefix).first()

序列化器（你可以看到我所有失败的尝试都被注释掉了：

class LocationSerializer(serializers.ModelSerializer):
    def get_client(self, obj):
        # return client_from_request(self.request)
        return client_from_request(self.context['request'])

    # client = serializers.SerializerMethodField('get_client')
    # client = serializers.SerializerMethodField()
    # client = serializers.Field(source='get_client', read_only=True)
    # client = serializers.ReadOnlyField(source='get_client')
    # client = serializers.PrimaryKeyRelatedField(read_only=True, default='get_client')
    client = serializers.PrimaryKeyRelatedField(read_only=True, source='get_client')
    # client = serializers.HiddenField(default=get_client(self))

    class Meta:
        model = Location
        fields = ['name', 'address', 'address2', 'city', 'state', 'zip_code', 'client']

视图集：

class LocationViewSet(viewsets.ModelViewSet):
    queryset = Location.objects.all()
    serializer_class = LocationSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        client = client_from_request(self.request)
        return super().get_queryset().filter(client=client)

你可以看到我尝试传递值的不同方式，但无论我做什么，我都会得到

IntegrityError at /locations/
null value in column "client_id" violates not-null constraint

Answer 1

将client 对象传递给序列化程序的一种简单方法是在perform_create 方法中传递它，类似于：

from rest_framework import serializers


class LocationViewSet(viewsets.ModelViewSet):
    queryset = Location.objects.all()
    serializer_class = LocationSerializer
    permission_classes = [permissions.IsAuthenticated]

    def get_queryset(self):
        client = client_from_request(self.request)
        return super().get_queryset().filter(client=client)

    def perform_create(self, serializer):
        client = client_from_request(self.request)
        if not client:
            raise serializers.ValidationError("Client does not exist")
        serializer.save(client=client)

并从您的序列化程序中删除客户端字段：

class LocationSerializer(serializers.ModelSerializer):

    class Meta:
        model = Location
        fields = ['name', 'address', 'address2', 'city', 'state', 'zip_code']

Answer 2

在您的视图集中，当您的 Location 模型没有 Client FK 时，您试图通过过滤 Client 来获取 Location。

就在这里：

def get_queryset(self):
        client = client_from_request(self.request)
        return super().get_queryset().filter(client=client) <----

正如上面评论中提到的@gregory，添加外键可以解决您的问题，然后您只需将其添加到您的序列化程序中即可。