Serialize Generic type over WCF Service

Question

I have a C# class defined as follows:

public class GenericItem<T>
{
  public List<T> Items { get; set; }

  public DateTime TimeStamp { get; set; }
} 

I am creating an instance of this class on my server. I am then trying to pass it over the wire via a WCF service as shown here:

[OperationContract]
public GenericItem<MyCustomType> GetResult()
{
  GenericItem<MyCustomType> result = BuildGenericItem();
  return result;
}

Everything compiles just fine at this point. When I "update service reference" in my Silverlight app an re-compile, I receive a compile-time error, similar to the following:

MyNamespace.GenericItemOfMyCustomType[extra chars] does not contain a public definition for 'GetEnumerator'

I have no idea why:

1. Extra chars are appearing. The seem to change everytime I update the service reference.
2. How to actually fix this.

What am I doing wrong?

Answer 1

Sleiman is correct, but one can use Bounded Generics as described in this article, and you may be able to achieve what you want. This allows you to create a generic type within the service and expose it. But the consumer will not view it as generic as the type is specified in the service operation.

Answer 2

You cannot define WCF contracts that rely on generic type parameters. Generics are specific to .NET, and using them would violate the service-oriented nature of WCF. However, a data contract can include a collection as a data member because WCF offers dedicated marshaling rules for collections.

Answer 3

As sleiman has pointed out, Generics are not supported in SOAP.

WCF and generics -> http://social.msdn.microsoft.com/Forums/en-US/wcf/thread/79585667-6b97-4ce4-93fa-3a4dcc7a9b86

related question -> WCF. Service generic methods