Python3.x 嵌套序列化程序 django rest 框架中的上下文

发布于06月01日

如果我有一个嵌套序列化程序:

class ChildSerializer(ModelSerializer):
    class Meta:
        fields = ('c_name', )
        model = Child


class ParentSerializer(ModelSerializer):

    child = ChildSerializer(many=True, read_only=True)

    class Meta:
        model = Parent
        fields = ('p_name', 'child')

我想访问嵌套序列化程序中的上下文，我该怎么做？据我所知，上下文并没有传递给子元素.

我希望能够在字段上实现每个用户的权限模型，为此我重写了ModelSerializer的get_fields()方法:

def get_fields(self):
    fields = super().get_fields()
    ....
    for f in fields:
        if has_rights(self.context['request'].user, f, "read"):
            ret_val[f] = fields[f]
    ....
    return ret_val

它适用于常规序列化程序，但在将嵌套子项传递给get_fields()时，上下文以及请求和用户不可用.当序列化程序嵌套时，如何访问上下文？

推荐答案

好的，我找到了一个有效的解决方案.我用SerializerMethodField替换了父类中的ChildSerializer赋值，后者添加了上下文.然后将其传递给CustomModelSerializer中的get_fields方法:

class ChildSerializer(CustomModelSerializer):
    class Meta:
        fields = ('c_name', )
        model = Child


class ParentSerializer(CustomModelSerializer):

    child = serializers.SerializerMethodField('get_child_serializer')

    class Meta:
        model = Parent
        fields = ('p_name', 'child')

    def get_child_serializer(self, obj):
        serializer_context = {'request': self.context.get('request') }
        children = Child.objects.all().filter(parent=obj)
        serializer = ChildSerializer(children, many=True, context=serializer_context)
        return serializer.data

在我的CustomModelSerializer中:

class CustomModelSerializer(rest_serializer_classes.HyperlinkedModelSerializer):

    def __init__(self, *args, **kwargs):
        """
            Make sure a user is coupled to the serializer (needed for permissions)
        """
        super().__init__(*args, **kwargs)
        if not self.context:
            self._context = getattr(self.Meta, 'context', {})
        try:
            self.user = self.context['request'].user
        except KeyError:
            self.user = None


    def get_fields(self):
        ret = OrderedDict()

        if not self.user:
            print("No user associated with object")
            return ret

        fields = super().get_fields()

        # Bypass permission if superuser
        if self.user.is_superuser:
            return fields

        for f in fields:
            if has_right(self.user, self.Meta.model.__name__.lower(), f, "read"):
                ret[f] = fields[f]

        return ret

这似乎很好，当我在Child.c_name或Parent.child上撤销读取权限时，序列化程序中会丢弃子字段