Django REST Framework按当前用户限制外键选择的问题求助

我查了好多资料、试了好几种方法都没用，试过限制外键可选范围和用CurrentUserDefault。我的需求是根据当前用户限制provider的可选范围，毕竟每个用户都有自己的provider。写了下面的Serializer和View代码后，运行报错：

TypeError: Field 'id' expected a number but got CurrentUserDefault(),

Serializer代码 #

class RideSerializer(serializers.ModelSerializer):

    invoice = InvoiceSerializer(required=False)
    duration = serializers.ReadOnlyField()
    riding_duration = serializers.ReadOnlyField()
    heading_duration = serializers.ReadOnlyField()
    earning_per_km = serializers.ReadOnlyField()
    earning_per_minute = serializers.ReadOnlyField()
    provider = serializers.PrimaryKeyRelatedField(
        queryset=User.objects.select_related(
            'driver_profile__team', 'company_profile__team').filter(
            Q(driver_profile__team__user=serializers.CurrentUserDefault()) |
            Q(Company_profile__team__user=serializers.CurrentUserDefault())),
        default=serializers.CurrentUserDefault())

    class Meta:
        model = Ride
        exclude = ['shift', ]
        read_only_fields = ['id', 'start_time', ]

View代码 #

class RideView(
        viewsets.GenericViewSet,
        mixins.UpdateModelMixin,
        mixins.RetrieveModelMixin,
        mixins.ListModelMixin,
        mixins.CreateModelMixin,):
    permission_classes = [IsDriver, ]
    serializer_class = RideSerializer
    http_method_names = ['post', 'patch', 'get']

    def get_queryset(self):
        return super().get_queryset().select_related(
            'shift', "invoice").filter(shift__driver=self.request.user.driver_profile)

    def create(self, request, *args, **kwargs):
        self.serializer = self.get_serializer(
            data=request.data, context={'request': request})
        return super().create(request, *args, **kwargs)

报错原因 #

CurrentUserDefault()是用来给字段设置默认值的工具，不能直接塞到查询集的filter条件里。序列化器初始化查询集时，还未获取到请求上下文，无法将CurrentUserDefault()解析为当前用户对象，导致把它当成普通实例传入，自然触发类型错误。

修改步骤 #

要动态获取当前用户过滤provider范围，我们可以自定义PrimaryKeyRelatedField，重写它的get_queryset方法来访问请求上下文：

1. 编写自定义字段类

from rest_framework import serializers
from django.db.models import Q

class UserFilteredPrimaryKeyRelatedField(serializers.PrimaryKeyRelatedField):
    def get_queryset(self):
        # 从上下文获取当前用户
        user = self.context['request'].user
        queryset = super().get_queryset()
        # 根据当前用户过滤provider可选范围
        return queryset.select_related(
            'driver_profile__team', 'company_profile__team'
        ).filter(
            Q(driver_profile__team__user=user) | 
            Q(company_profile__team__user=user)  # 原代码的Company_profile需改为小写，符合Django字段命名规范
        )

2. 更新RideSerializer中的provider字段

class RideSerializer(serializers.ModelSerializer):

    invoice = InvoiceSerializer(required=False)
    duration = serializers.ReadOnlyField()
    riding_duration = serializers.ReadOnlyField()
    heading_duration = serializers.ReadOnlyField()
    earning_per_km = serializers.ReadOnlyField()
    earning_per_minute = serializers.ReadOnlyField()
    # 使用自定义字段类，基础查询集设为User.objects.all()，后续动态过滤
    provider = UserFilteredPrimaryKeyRelatedField(
        queryset=User.objects.all(),
        default=serializers.CurrentUserDefault()
    )

    class Meta:
        model = Ride
        exclude = ['shift', ]
        read_only_fields = ['id', 'start_time', ]

3. 额外注意

• 原代码中Q(Company_profile__team__user=...)的Company_profile需改为小写company_profile，否则Django会提示字段不存在。
• 你的View中create方法已将request传入上下文，其他方法（如update）GenericViewSet会默认处理，无需额外修改。

内容的提问来源于stack exchange，提问作者usama Shehab