有没有理由为什么用XmlInclude修饰的基类在序列化时仍会抛出类型未知异常？

Question

我将简化代码以节省空间,但所呈现的内容确实说明了核心问题.

我有一个类,它有一个基类型的属性.有3个派生类可以分配给该属性.

如果我将任何派生类分配给容器并尝试序列化容器,则XmlSerializer会抛出可怕的:

"不期望类型x.使用XmlInclude或SoapInclude属性指定静态未知的类型."

但是我的基类已经用该属性修饰,所以我认为必须有一个额外的"隐藏"要求.

真正奇怪的是,默认的WCF序列化程序对此类层次结构没有任何问题.

Container类

[DataContract]
[XmlRoot(ElementName = "TRANSACTION", Namespace = Constants.Namespace)]
public class PaymentSummaryRequest : CommandRequest
{
    [DataMember]
    public PaymentSummary Summary { get; set; }

    public PaymentSummaryRequest()
    {
        Mechanism = CommandMechanism.PaymentSummary;
    }
}

基类

[DataContract]
[XmlInclude(typeof(xPaymentSummary))]
[XmlInclude(typeof(yPaymentSummary))]
[XmlInclude(typeof(zPaymentSummary))]
[KnownType(typeof(xPaymentSummary))]
[KnownType(typeof(yPaymentSummary))]
[KnownType(typeof(zPaymentSummary))]
public abstract class PaymentSummary
{     
}

派生类之一

[DataContract]
public class xPaymentSummary : PaymentSummary
{
}

序列化代码

var serializer = new XmlSerializer(typeof(PaymentSummaryRequest));
serializer.Serialize(Console.Out,new PaymentSummaryRequest{Summary = new xPaymentSummary{}});

例外

System.InvalidOperationException:生成XML文档时出错.---> System.InvalidOperationException:不期望类型为xPaymentSummary.使用XmlInclude或SoapInclude属性指定静态未知的类型.在

Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterPaymentSummaryRequest.Write13_PaymentSummary(String n,String ns,PaymentSummary o,Boolean isNullable,Boolean needType)at at

Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterPaymentSummaryRequest.Write14_PaymentSummaryRequest(String n,String ns,PaymentSummaryRequest o,Boolean isNullable,Boolean needType)at at

Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterPaymentSummaryRequest.Write15_TRANSACTION(对象O)---内部异常堆栈跟踪的末尾在

System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter,Object o,XmlSerializerNamespaces namespaces,String encodingStyle,String id)at

System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter,Object o,XmlSerializerNamespaces名称空间)
位于c:\ Users\Tedford\AppData\Local\Temp\uqacncyo.0.cs中的UserQuery.RunUserAuthoredQuery():第47行

Answer 1

您看到的问题是因为PaymentSummaryRequest正在设置命名空间.您可以删除命名空间或向PaymentSummary类添加命名空间:

[XmlRoot(Namespace = Constants.Namespace)]
[XmlInclude(typeof(xxxPaymentSummary))]
public abstract class PaymentSummary
{
}

正如@Tedford在下面的评论中提到的,只有在使用派生类型时才需要命名空间.

在生成XML序列化程序集时,由于Root节点具有名称空间集而基类不存在,因此它不会在生成的序列化程序集中包含XML Include逻辑.

解决该问题的另一种方法是从类本身中删除名称空间声明,并在XmlSerializer构造函数上指定名称空间:

var serializer = new XmlSerializer(
    typeof(PaymentSummaryRequest), 
    Constants.Namespace
);