Django Rest Framework 插入和更新可写嵌套序列化程序

Question

我尝试使用 Django Rest Framework 插入和更新一个可写的嵌套序列化程序，遵循 this 之类的示例。但它不起作用，因为在我执行 serializer.is_valid() 之后，它会丢失来自 serializer.validated_data 的引用，就像它从未发送过一样。

我做错了什么？

我的模型

class User(AbstractUser):

    institution = models.ForeignKey(Institution, on_delete=None, null=True, blank=True)

    class Meta:
        db_table = 'User'
        managed = True
        verbose_name = 'Users'
        verbose_name_plural = 'Users'
        ordering = ['id']

    def __str__(self):
        return self.email

class Institution(models.Model):
    id = models.AutoField(db_column='id', primary_key=True)
    name = models.CharField(db_column='name', max_length=255, null=False)
    country = models.CharField(db_column='country', max_length=255, null=False)

    class Meta:
        db_table = 'Institution'
        managed = True
        verbose_name = 'Institutions'
        verbose_name_plural = 'Institutions'
        ordering = ['id']

    def __str__(self):
        return self.name

我的序列化器

class InstitutionSerializer(serializers.ModelSerializer):

    class Meta:
        model = Institution
        fields = '__all__'
        datatables_always_serialize = ('id', 'name', 'country')

class UserSerializer(serializers.HyperlinkedModelSerializer):
    institution = InstitutionSerializer()

    def create(self, validated_data):
        return User.objects.create_user(**validated_data)

    def update(self, instance, validated_data):
        institution_data = validated_data['institution']
        instance.institution = Institution.objects.get(pk=institution_data['id'])
        return instance

    class Meta:
        model = User
        fields = (
            'id',
            'username',
            'first_name',
            'last_name',
            'email',
            'password',
            'is_active',
            'institution',
        )
        datatables_always_serialize = (
            'id',
            'username',
            'first_name',
            'last_name',
            'email',
            'is_active',
            'institution',
        )

我的看法

class UserViewSet(ModelViewSet):
    serializer_class = UserSerializer
    permission_classes = (IsSuperUserPermission,)

    def list(self, request, **kwargs):
        params = Q()
        if 'search[value]' in request.GET and request.GET['search[value]'] != '':
            params = Q(username__icontains=request.GET['search[value]']) |\
                     Q(first_name__icontains=request.GET['search[value]']) |\
                     Q(last_name__icontains=request.GET['search[value]']) |\
                     Q(email__icontains=request.GET['search[value]']) |\
                     Q(institution__name__icontains=request.GET['search[value]'])

        queryset = User.objects.filter(params).select_related().order_by('id')
        serializer = self.serializer_class(queryset, many=True)
        return Response(serializer.data)

    def retrieve(self, request, *args, **kwargs):
        queryset = User.objects.filter(pk=request.GET['pk']).select_related()
        serializer = UserSerializer(queryset, many=True)
        return Response(serializer.data)

    def get_permissions(self):
        if self.action in ('create',):
            self.permission_classes = [AllowAny, ]
        return super(self.__class__, self).get_permissions()

    def create(self, request, *args, **kwargs):
        serializer = UserSerializer(data=request.data)
        if serializer.is_valid():
            serializer.create(serializer.validated_data)
            return Response(serializer.data)
        else:
            return Response(serializer.errors, status.HTTP_500_INTERNAL_SERVER_ERROR)

    def partial_update(self, request, *args, **kwargs):
        user = User.objects.get(pk=request.data['id'])
        serializer = UserSerializer(instance=user, data=request.data, partial=True)
        if serializer.is_valid():

            if 'password' in serializer.validated_data:
                serializer.validated_data['password'] = make_password(serializer.validated_data['password'])

            serializer.update(user, serializer.validated_data)
            return Response(serializer.data)
        else:
            return Response(serializer.errors, status.HTTP_500_INTERNAL_SERVER_ERROR)

编辑。

我这样提交数据：

{
    "username": "BLA",
    "email": "BLA@BLA.com",
    "first_name": "BLA",
    "last_name": "BLA",
    "institution": 1,
    "is_active": true,
    "password": "bla12345"
}

Answer 1

为什么会出现这个问题？

在您的更新负载中，您将 institution 数据提供为代表 PK 的整数。但是您还在 UserSerializer() 类中定义了一个嵌套的序列化器 InstitutionSerializer()。因此，DRF 需要一个类似 dict 的对象（DRF 可能会通过提及这一点引发一些错误。我不确定为什么在这种情况下没有发生这种情况）。

解决办法是什么？

由于您传递的是机构 ID，我假设您只需要在HTTP GET 请求中嵌套输出。因此，覆盖 UserSerializer() 类的 __init__() 方法并将嵌套序列化程序的使用限制为仅 HTTP GET 请求

这是代码

class UserSerializer(serializers.HyperlinkedModelSerializer):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        if self.context['request'].method == 'GET':
            self.fields['institution'] = InstitutionSerializer()

    institution = InstitutionSerializer() # remove this

    def create(self, validated_data):
        return User.objects.create_user(**validated_data)

    def update(self, instance, validated_data):
        institution_data = validated_data['institution']
        instance.institution = Institution.objects.get(pk=institution_data['id'])
        return instance

    class Meta:
        model = User
        fields = (
            'id',
            'username',
            'first_name',
            'last_name',
            'email',
            'password',
            'is_active',
            'institution',
        )
        datatables_always_serialize = (
            'id',
            'username',
            'first_name',
            'last_name',
            'email',
            'is_active',
            'institution',
        )

---

更新-1

如下更改 UserViewSet 类的 partial_update() 方法，

def partial_update(self, request, *args, **kwargs):
    user = User.objects.get(pk=request.data['id'])
    serializer = UserSerializer(instance=user, data=request.data, partial=True, context={"request": request}) # change is here &lt&lt&lt
    if serializer.is_valid():

        if 'password' in serializer.validated_data:
            serializer.validated_data['password'] = make_password(serializer.validated_data['password'])

        serializer.update(user, serializer.validated_data)
        return Response(serializer.data)
    else:
        return Response(serializer.errors, status.HTTP_500_INTERNAL_SERVER_ERROR)

Answer 2

我找到了一种方法来解决我的问题，使用 JPG 的想法。我只是使用 PrimaryKeyRelatedField 添加了一个 else 以允许序列化程序从 id 获取模型的引用。 可能还有另一种解决方案，但这个解决方案比多个序列化程序更有效且看起来更好。

class UserSerializer(serializers.HyperlinkedModelSerializer):
    def __init__(self, *args, **kwargs):
        super().__init__(*args, **kwargs)
        if self.context['request'].method == 'GET':
            self.fields['institution'] = InstitutionSerializer()
        else:
            self.fields['institution'] = serializers.PrimaryKeyRelatedField(queryset=Institution.objects.all())