Asp.net WCF&；亚音速类-反序列化器没有任何类型的知识映射到此合同

我的WCF客户端出现以下错误：

"Error in line 1 position 1910. Element 'http://schemas.datacontract.org/2004/07/SubSonic:_currentValue' contains data of the 'http://schemas.datacontract.org/2004/07/System:DBNull' data contract. The deserializer has no knowledge of any type that maps to this contract. Add the type corresponding to 'DBNull' to the list of known types - for example, by using the KnownTypeAttribute attribute or by adding it to the list of known types passed to DataContractSerializer."

我正在使用亚音速2.0生成我的类对象

我还使用

DataContract

和

DataMember

装饰了我的类和成员

已尝试将

[KnownType（typeof（System.DBNull））]

添加到生成的类中

已尝试将

[ServiceKnownType（typeof（System.DBNull））]

添加到我的服务界面

我生成的类如下所示：（该类是为SQL视图生成的）

所以，当反序列化客户端未获得System.DBNull类型时。我们必须在客户端配置文件中添加knowntypes

客户端需要此配置，解决了我的问题：

<system.runtime.serialization>
        <dataContractSerializer>    
            <declaredTypes>
                <add type="NameSpace.ServiceClientName.ClassNameForWhichKnownTypeIsToBeGiven, AssemblyName">
                    <knownType  type="System.DBNull"></knownType>
                </add>
             </declaredTypes>
        </dataContractSerializer>
</system.runtime.serialization> 

希望这将是有用的人

 [ServiceContract]    
    [ServiceKnownType(typeof(System.DBNull))]    
    public interface IPatientService
    {
        [WebInvoke(Method = "GET", UriTemplate = "GetPatientAppointments")]
        [OperationContract]
        IList<VwPatientRt> GetPatientAppointments();
     ..... 

public class PatientService : IPatientService
{ 
    public IList<VwPatientRt> GetPatientAppointments()
    {
       ... .
       .....
    }
   ... 

[ServiceKnownType(typeof(System.DBNull))] 

<system.runtime.serialization>
        <dataContractSerializer>    
            <declaredTypes>
                <add type="NameSpace.ServiceClientName.ClassNameForWhichKnownTypeIsToBeGiven, AssemblyName">
                    <knownType  type="System.DBNull"></knownType>
                </add>
             </declaredTypes>
        </dataContractSerializer>
</system.runtime.serialization>