如何向嵌套序列化程序添加默认值？

我试图让我的“地址”API 返回默认值（空字符串“”），但是当我在序列化程序字段中使用 default="" 时，它返回 null。这是我的主要序列化程序（LocationSerializer）

class LocationSerializer(serializers.ModelSerializer):
    id = serializers.UUIDField(read_only=True)
    business_id = serializers.PKRelatedField(Business.any.all(), "business")
    city_id = serializers.UUIDField(required=True)
    name = serializers.CharField(max_length=48, required=True)
    tax_number = serializers.CharField(max_length=48)
    phone = serializers.PhoneNumberField()
    address = serializers.CharField()
    address_details = AddressEmbeddedSerializer(default="", source="addresses")
    footer = serializers.CharField()
    is_active = serializers.BooleanField(required=True)
    has_kds = serializers.BooleanField(read_only=True)
    position = serializers.PointField()
    image = serializers.ImageField()
    # profile = LocationProfileSerializer()
    permissions = PermissionSerializer(many=True, read_only=True)
    payment_methods = PaymentMethodEmbeddedSerializer(many=True, read_only=True)

    class Meta:
        model = Location
        fields = (
            "id", "business_id", "city_id", "name", "tax_number", "phone", "address", "address_details", "footer",
            "is_active", "has_kds", "position", "image", "permissions", "payment_methods"
        )

这是我的嵌套序列化器（AddressEmbeddedSerializer）

class AddressEmbeddedSerializer(serializers.ModelSerializer):
    city = serializers.CharField(default="")
    area = serializers.CharField(default="")
    block = serializers.CharField(default="")
    avenue = serializers.CharField(default="")
    long = serializers.CharField(default="")
    lat = serializers.CharField(default="")

    class Meta:
        model = LocationAddress
        fields = (
            "city", "area", "block", "avenue", "long", "lat"
        )

我期待的价值是：

"address_details": {
            "city": "",
            "area": "",
            "block": "",
            "avenue": "",
            "long": "",
            "lat": ""
        }

相反，我得到的是：

"address_details": null

请注意所有 CRUD 操作都在工作，这只是一个默认值问题