Question

我有一些使用dataContracts的WCF服务，我希望我希望通过自定义Dictionary＆lt;传递一个Exception。 string，object＆gt; Data属性中的数据，但是当我在抛出之前在此数组上添加任何数据时，我在自定义ServiceBehavior的ErrorHandler中收到以下错误：

Type 'System.Collections.ListDictionaryInternal'
带有数据合同名称 'ArrayOfKeyValueOfanyTypeanyType：HTTP：//schemas.microsoft.com/2003/10/Serialization/Arrays' 不是预期的。不添加任何类型静态地知道已知的名单类型 - 例如，通过使用 KnownTypeAttribute属性或将它们添加到已知类型列表中传递给DataContractSerializer。

我是否总是需要创建一个带有注释为DataContract的Dictionary属性的自定义异常并抛出它？使用ErrorHandler的想法是避免在每个服务方法中处理异常，我还需要在方法中添加更多注释吗？我错过了什么？

供参考，这是我的FaultErrorHandler类：

public class FaultErrorHandler : BehaviorExtensionElement, IErrorHandler, IServiceBehavior
    {
        public bool HandleError(Exception error)
        {
            if (!Logger.IsLoggingEnabled()) return true;
            var logEntry = new LogEntry
            {
                EventId = 100,
                Severity = TraceEventType.Error,
                Priority = 1,
                Title = "WCF Failure",
                Message = string.Format("Error occurred: {0}", error)
            };
            logEntry.Categories.Add("MiddleTier");

            Logger.Write(logEntry);
            return true;
        }

        public void ProvideFault(Exception error, System.ServiceModel.Channels.MessageVersion version, ref System.ServiceModel.Channels.Message fault)
        {
            var faultException = new FaultException<Exception>( error, new FaultReason(string.Format("System error occurred, exception: {0}", error)));
            var faultMessage = faultException.CreateMessageFault();
            fault = Message.CreateMessage(version, faultMessage, Schema.WebServiceStandard);
        }

        public void AddBindingParameters(ServiceDescription serviceDescription, System.ServiceModel.ServiceHostBase serviceHostBase, System.Collections.ObjectModel.Collection<ServiceEndpoint> endpoints, System.ServiceModel.Channels.BindingParameterCollection bindingParameters)
        {
        }

        public void ApplyDispatchBehavior(ServiceDescription serviceDescription, System.ServiceModel.ServiceHostBase serviceHostBase)
        {
            foreach (ChannelDispatcher chanDisp in serviceHostBase.ChannelDispatchers)
            {
                chanDisp.ErrorHandlers.Add(this);
            };
        }

        public void Validate(ServiceDescription serviceDescription, System.ServiceModel.ServiceHostBase serviceHostBase)
        {
        }

        public override Type BehaviorType
        {
            get { return typeof(FaultErrorHandler); }
        }

        protected override object CreateBehavior()
        {
            return new FaultErrorHandler();
        }
    }

我的典型服务界面如下：

[ServiceContract(Name = "Service", Namespace = Schema.WebServiceStandard, SessionMode = SessionMode.Allowed)]
    public interface IService 
    {

        [OperationContract(Name = "GetSomething")]
        [FaultContract(typeof(ValidationFault))]
        LookupResult GetSomething();
    }

Answer 1

System.Exception实现了ISerializable，它由序列化程序以与Dictionary相同的方式处理 - 它可以被[de]序列化，但你需要告诉序列化器哪些类型将被[de]序列化。在异常情况下，您无法更改类声明，因此如果您希望使此方案有效，则需要在服务合同中添加已知类型（使用[ServiceKnownType]）以用于该类用于Data属性（使用内部类型System.Collections.ListDictionaryInternal）以及您将添加到数据字典的任何类型。下面的代码显示了如何做到这一点（虽然我真的建议不要这样做，你应该定义一些DTO类型来处理需要返回的信息，以防止必须处理Exception类的内部实现细节

public class StackOverflow_6552443
{
    [DataContract]
    [KnownType("GetKnownTypes")]
    public class MyDCWithException
    {
        [DataMember]
        public Exception myException;

        public static MyDCWithException GetInstance()
        {
            MyDCWithException result = new MyDCWithException();
            result.myException = new ArgumentException("Invalid value");
            result.myException.Data["someData"] = new Dictionary<string, object>
            {
                { "One", 1 },
                { "Two", 2 },
                { "Three", 3 },
            };
            return result;
        }

        public static Type[] GetKnownTypes()
        {
            List<Type> result = new List<Type>();
            result.Add(typeof(ArgumentException));
            result.Add(typeof(Dictionary<string, object>));
            result.Add(typeof(IDictionary).Assembly.GetType("System.Collections.ListDictionaryInternal"));
            return result.ToArray();
        }
    }
    [ServiceContract]
    public interface ITest
    {
        [OperationContract]
        MyDCWithException GetDCWithException();
    }
    public class Service : ITest
    {
        public MyDCWithException GetDCWithException()
        {
            return MyDCWithException.GetInstance();
        }
    }
    public static void Test()
    {
        string baseAddress = "http://" + Environment.MachineName + ":8000/Service";
        ServiceHost host = new ServiceHost(typeof(Service), new Uri(baseAddress));
        host.AddServiceEndpoint(typeof(ITest), new BasicHttpBinding(), "");
        host.Open();
        Console.WriteLine("Host opened");

        ChannelFactory<ITest> factory = new ChannelFactory<ITest>(new BasicHttpBinding(), new EndpointAddress(baseAddress));
        ITest proxy = factory.CreateChannel();

        Console.WriteLine(proxy.GetDCWithException());

        ((IClientChannel)proxy).Close();
        factory.Close();

        Console.Write("Press ENTER to close the host");
        Console.ReadLine();
        host.Close();
    }
}

Answer 2

您还必须为可能添加到[KnownType]的任何非系统类型添加Dictionary<string , object>属性。例如，如果您向字典添加MyType，则需要添加[KnownType(typeof(MyType))]。

System.Exception.Data不会在DataContract上串行化？

2 个答案: