如何使用KnownType 在WCF 服务合同中启用多态返回值? [英] How do I use KnownType to enable polymorphic return values in a WCF service contract?

问题描述

我正在将远程接口转换为 WCF，但是我有一个方法声明为返回对象"并且可以返回许多不同的类型(主要是不同的枚举)

I am converting a remoting interface to WCF, however I have a method that is declared to return "object" and can return a number of different types (mostly different enums)

在哪里可以找到应对此问题的示例?

Where can I find an example of coping with this?

(我正在使用包含所有类型的共享合约程序集，而不是生成客户端代理，如果这有所不同.)

(I am using a shared contract assembly that contains all the types rather than generating a client proxy if that makes a difference.)

推荐答案

这就是我最后所做的，但是我很高兴开始使用 Aaron Fischer 长期提供的解决方案之一.

This is what I did in the end, however I am lickly to start using one of the soltuions that Aaron Fischer gave in the long term.

/// <summary>
/// WCF can not cope with a method that returns an object so wrap the
/// untyped object in a typed object.  Then use KnowType to tell WCF 
/// about the typs that are wrapped
/// </summary>
[DataContract(), KnownType(typeof(MyType1)), KnownType(typeof(MyType2))]
public class UntypedObjectHolder
{
    [DataMember()]
    private object m_Value;

    public UntypedObjectHolder(object value)
    {
        m_Value = value;
    }

    public object Value
    {
        get { return m_Value; }
    }
}

然后在我的界面中

[OperationContract()]
UntypedObjectHolder GetValue(eGetValueType valueType);

<小时>

我没有尝试过的另一个可能有效的选项是

---

Another option that may work that I did not try is

[ServiceContract]
[ServiceKnownType(typeof(PhotoCamera))]
[ServiceKnownType(typeof(TemperatureSensor))]
[ServiceKnownType(typeof(DeviceBase))]
public interface IHomeService
{    
   [OperationContract] IDevice GetInterface();
}

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