WCF OperationContract with loosely typed parameter

c#, operationcontract, wcf

Solution

I have just done this, I found you need to add the KnownTypesAttribute to the interface.

[ServiceContract]
[ServiceKnownType(typeof(MyContract1)]
[ServiceKnownType(typeof(MyContract2)]
[ServiceKnownType(typeof(MyContract3)]
public interface IMyService
{
    [OperationContract]
    object TakeMessage();

    [OperationContract]
    void AddMessage(object contract);

}

in you implementation, you will need to check the type to ensure it is one of your DataContracts.

EDIT

If you have a lot of contracts, you can use reflection to add them to the KnownTypes.

internal static class KnownTypeHelper
{
    public static IEnumerable<Type> GetKnownTypes(ICustomAttributeProvider provider = null)
    {
        var types = Assembly.GetExecutingAssembly().GetTypes().Where(a => a.Namespace == "Company.Path.To.DataContractsNamespace").ToArray();

        return types;
    }
}

Then you can declare your interface as,

[ServiceContract]
[ServiceKnownType("GetKnownTypes", typeof(KnownTypeHelper))]
public interface IMyService
{
    [OperationContract]
    object TakeMessage( );

    [OperationContract]
    void AddMessage(object contract);
}

This is a much cleaner way of doing it.

Problem

I want a loosely typed parameter in my web method. I have a scenario where the client can send any of 25 DataContract objects into the WCF operation e.g. ``` proxy1.myFunction(PersonObject) proxy1.myFunction(ComputerObject) ``` My restriction is there should be only one Operation Contract exposed to the client. How can I design a web method which can take any of the 25 DataContract classes as a parameter? I tried with `object` as type of parameter and gave `KnownType` attribute to the DataContract classes but I had no luck during the serialization process.

Original source