Stream 通过WCF传输文件时发生ArgumentNullException

我有一个WCF流二进制文件。以下是合同的缩略版本

[MessageContract()]
public class DocumentTransfer
{
    [MessageHeader(MustUnderstand = true)]
    public string Title { get; set; }

    [MessageHeader(MustUnderstand = true)]
    public string FileName { get; set; }

    [MessageBodyMember(Order = 1)]
    public System.IO.Stream Data;
}

一切正常，但在某些情况下，只需要更新与文件关联的一些其他值，而不需要更新文件本身。在这种情况下，客户端将Data设置为null。因此无法解释/序列化数据属性，并引发此异常：

System.ServiceModel.Dispatcher.StreamFormatter.Serialize(XmlDictionaryWriter writer, Object[] parameters, Object returnValue)
System.ServiceModel.Dispatcher.OperationFormatter.SerializeBodyContents(XmlDictionaryWriter writer, MessageVersion version, Object[] parameters, Object returnValue, Boolean isRequest)
System.ServiceModel.Dispatcher.OperationFormatter.OperationFormatterMessage.OperationFormatterBodyWriter.OnWriteBodyContents(XmlDictionaryWriter writer)
System.ServiceModel.Channels.BodyWriter.WriteBodyContents(XmlDictionaryWriter writer)
System.ServiceModel.Channels.BodyWriterMessage.OnWriteBodyContents(XmlDictionaryWriter writer)
System.ServiceModel.Channels.Message.OnWriteMessage(XmlDictionaryWriter writer)
System.ServiceModel.Channels.Message.WriteMessage(XmlDictionaryWriter writer)
System.ServiceModel.Channels.TextMessageEncoderFactory.TextMessageEncoder.WriteMessage(Message message, Stream stream)
System.ServiceModel.Channels.HttpOutput.WriteStreamedMessage(TimeSpan timeout)
System.ServiceModel.Channels.HttpOutput.Send(TimeSpan timeout)
System.ServiceModel.Channels.HttpChannelFactory.HttpRequestChannel.HttpChannelRequest.SendRequest(Message message, TimeSpan timeout)
System.ServiceModel.Channels.RequestChannel.Request(Message message, TimeSpan timeout)
System.ServiceModel.Dispatcher.RequestChannelBinder.Request(Message message, TimeSpan timeout)
System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs, TimeSpan timeout)
System.ServiceModel.Channels.ServiceChannel.Call(String action, Boolean oneway, ProxyOperationRuntime operation, Object[] ins, Object[] outs)
System.ServiceModel.Channels.ServiceChannelProxy.InvokeService(IMethodCallMessage methodCall, ProxyOperationRuntime operation)
System.ServiceModel.Channels.ServiceChannelProxy.Invoke(IMessage message)
System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
...UploadDocument(DocumentTransfer request)
...UploadDocument(DocumentTransfer request) in ...

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有什么想法吗？

当正文为空时，您将在序列化BodyContents中获得错误

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您可以在没有文件时为创建不同的操作，也可以在流中放入一个字节以避免异常。第一个选项更可取，如果您无法更改合同，则最后一个选项更可取。

另一个选项是返回Stream.Null。

使用不同的类型-

DocumentMetadataTransfer

或其他类型。这是有理由的，因为正如你所解释的，它们适合不同的用途。只有标题的邮件现在不完全是邮件了，是吗？另外，

Title

和

FileName

不应该是

MessageHeader

项，因为它们实际上是消息的一部分，不一定是消息元数据，而是操作数据。

[MessageContract()]
public class DocumentTransfer
{
    [MessageHeader(MustUnderstand = true)]
    public string Title { get; set; }

    [MessageHeader(MustUnderstand = true)]
    public string FileName { get; set; }

    [MessageBodyMember(Order = 1)]
    public System.IO.Stream Data;
}