Question

In a Web Service context, I have the following class which inherit from the class Mammal. The Mammal class is defined in a proxy. I cannot change the definition of that class. Because I need to add some methods to the class Mammal on the client side, I inherited Mammal and created Giraffe.

namespace TestApplication {       public class Giraffe : Mammal     {         public Giraffe()         {         }     } } 

When I call a WebMethod which expect an object of type Mammal, I get the following exception telling me that Giraffe isn’t expected.

  Error: System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: The type Giraffe was not expected. Use the XmlInclude or SoapInclude attribute to specify types that are not known statically.    at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterPaymentRequestAuthorization.Write6_Tender(String n, String ns, Tender o, Boolean isNullable, Boolean needType)    at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterPaymentRequestAuthorization.Write12_PaymentRequestAuthorization(String n, String ns, PaymentRequestAuthorization o, Boolean isNullable, Boolean needType)    at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriterPaymentRequestAuthorization.Write13_PaymentRequestAuthorization(Object o)    --- End of inner exception stack trace --- 

Is there a workaround that? I cannot really add the XmlInclude…

Answer 1

To add methods, you should be using partial classes. Try adding a second class file with (in the right namespace etc):

partial class Mammal {     public void ExtraMethod() {...} } 

The partial keyword tells the compiler to allow the class to be split over multiple files – ideal for code-generation scenarios. It does, however, demand the partial keyword in every file; the members are simply combined (except for partial methods in C# 3.0 which have their own subtle behaviour). I hope that wsdl.exe (or whatever) includes this!