如何将Child子类以Base基类形式传给WCF服务避免序列化异常？

服务器端代码：

[DataContract]
public class Base { }

[OperationContract]
void DoSth(Base base) { }

客户端代码：

class Child : Base { }

调用DoSth(child)时触发序列化异常：

System.ServiceModel.CommunicationException: There was an error while trying to serialize parameter http://tempuri.org/:base. The InnerException message was 'Type 'Child' with data contract name 'Child:http://schemas.datacontract.org/2004/07/Client' is not expected. Add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.'. Please see InnerException for more details.
---> System.Runtime.Serialization.SerializationException: Type 'Child' with data contract name 'Child:http://schemas.datacontract.org/2004/07/Client' is not expected. Add any types not known statically to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding them to the list of known types passed to DataContractSerializer.

需求：服务器仅用到Base的属性，不想把Child设为已知类型，希望优雅地将数据以Base对象形式发送，无需手动复制属性。尝试过给Child添加[DataContract(Name = "Base", Namespace = "http://schemas.datacontract.org/2004/07/Server")]但无效。

方案1：自定义类型转换运算符 #

在客户端的Child类中定义显式转换到Base的运算符，将属性复制逻辑封装在类内部，外部调用更简洁：

class Child : Base
{
    // 示例属性，根据实际Base类属性调整
    public string Name { get; set; }
    public int Age { get; set; }

    public static explicit operator Base(Child child)
    {
        return new Base
        {
            Name = child.Name,
            Age = child.Age
        };
    }
}

调用时直接转换：

var child = new Child { Name = "Tom", Age = 25 };
service.DoSth((Base)child);

方案2：使用AutoMapper自动映射 #

如果实体属性较多，手动编写转换逻辑繁琐，可借助AutoMapper自动完成Child到Base的属性映射：

1. 安装AutoMapper NuGet包：Install-Package AutoMapper
2. 配置映射关系：

var mapperConfig = new MapperConfiguration(cfg => 
{
    cfg.CreateMap<Child, Base>(); // 自动匹配同名属性
});
var mapper = mapperConfig.CreateMapper();

3. 调用时完成映射：

var child = new Child();
var baseObj = mapper.Map<Base>(child);
service.DoSth(baseObj);

方案3：自定义客户端序列化器 #

直接修改客户端的DataContractSerializer，强制按Base类型序列化Child对象，无需修改实体类或服务端：

var serviceClient = new YourServiceClient();

// 获取并替换客户端的序列化行为
var serializerBehavior = serviceClient.Endpoint.Behaviors.Find<DataContractSerializerOperationBehavior>();
serializerBehavior.DataContractSerializer = new DataContractSerializer(typeof(Base));

// 执行调用
serviceClient.DoSth(child);
serviceClient.Close();

这种方式让序列化器忽略Child的具体类型，只序列化Base中定义的属性，服务端就能正常解析。

内容的提问来源于stack exchange，提问作者Achim Stuy