c# - 为什么 WCF 不能传递字典中的对象？

Question

在我的 WCF 服务中，我将对象 QualifiedNumber 定义为 KnownType 和 ServiceKnown 类型。如果我在以下方法中使用 QualifiedNumber:

这个不行。它抛出一个异常，部分内容如下:

Element 'http://schemas.microsoft.com/2003/10/Serialization/Arrays:Value' contains data of the 'http://schemas.datacontract.org/2004/07 ServiceLibrary.Web.Model:QualifiedNumber' data contract. The deserializer has no knowledge of any type that maps to this contract. cannot deserialize because the definition of QualifiedNumber is not known.

[OperationContract]
public Dictionary<int, object> TestDictionaryGet()
{
    Dictionary<int, object> retDict = new Dictionary<int, object>();

    retDict.Add(1, new QualifiedNumber(new decimal(1.2), "<"));
    retDict.Add(2, "pass a simple string");

    return retDict;
}

这个确实有效

public struct element
{
    public int key;
    public object value;
}

[OperationContract]
public List<element> TestElementListGet()
{
    Dictionary<int, object> retDict = new Dictionary<int, object>();

    retDict.Add(1, new QualifiedNumber(new decimal(1.2), "<"));
    retDict.Add(2, "pass a simple string");

    List<element> retElements = new List<element>();
    foreach (KeyValuePair<int, object> item in retDict)
    {
        element newElement;
        newElement.key = item.Key;
        newElement.value = item.Value;

        retElements.Add(newElement);
    }

    return retElements;
}

导致异常的字典是什么？

Answer 1

这是一篇关于通过 WCF 进行通用字典序列化的详细文章:

http://www.request-response.com/blog/PermaLink,guid,ff5fab81-affb-4b2b-aa67-c80bdfc86cbd.aspx

那篇文章的要点是:

There is no way to meaningfully convey the semantics of a .NET dictionary class using WSDL/XSD.