"ServiceKnownType" attribute is missing from generated file

Question

Hi

becuase of complex type in service params (in,out) I had to decorate the service Operation contract with "ServiceKnownType" attribute.

The problem is that when i heat add service refference to generate proxi class that attribute dows' t apear in generated interface.

 

when I run the app it throw exeption about known type.

 so i added it manualy and every thing work...

 

of course that every time i doing update web refference i have to do it again.

 

any short cut idea?

 

thanks

Answer 1

Can you post a small sample of the ServiceContract and KnownTypes that reproduces the issue?

Answer 2

Hi, sorry for delay

here is some code. base on clean wcf project with some changes marked with color

contract

 

[ServiceContract]

public interface IService1

{

[OperationContract]

string GetData(int intParam);

 

[OperationContract]

[ServiceKnownType (typeof(CompositeType))]

Dictionary<string,object> GetDataUsingDataContract(CompositeType composite);

}

 

implement

public Dictionary<string,object> GetDataUsingDataContract(CompositeType composite)

{

Dictionary<string, object> res = new Dictionary<string, object>();

res.Add("Third", new CompositeType { BoolValue = false, StringValue = "Hi" });

return res;

}

 

client

static void Main(string[] args)

{

ServiceReference.Service1Client proxy = new Client.ServiceReference.Service1Client();

Dictionary<string,object> obj = proxy.GetDataUsingDataContract(null);

}

 

now when running I get an exeption with that message :

 

The formatter threw an exception while trying to deserialize the message: There was an error while trying to deserialize parameter http://tempuri.org/:GetDataUsingDataContractResult. The InnerException message was 'Error in line 1 position 573. Element 'http://schemas.microsoft.com/2003/10/Serialization/Arrays:Value' contains data of the 'http://schemas.datacontract.org/2004/07/Server:CompositeType' data contract. The deserializer has no knowledge of any type that maps to this contract. Add the type corresponding to 'CompositeType' 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.'.  Please see InnerException for more details.

 

to fix it I need to add manualy to reference.cs (hidden in solution explorer) under service reference->MyService->Reference.svcmap->reference.cs

in the IService1 section that attribute:

 

[ServiceKnownType(typeof(CompositeType))]

[System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/IService1/GetDataUsingDataContract", ReplyAction="http://tempuri.org/IService1/GetDataUsingDataContractResponse")]System.Collections.Generic.Dictionary<string, object> GetDataUsingDataContract(Client.ServiceReference.CompositeType composite);

 

and it work correct.

 

thanks

Adiel

Answer 3

Hi I came across your article because I had the same problem. A few search results down on Google linked to a blog post that solved the problem for me.

http://softwareblog.alcedo.com/2010/01/default.aspx

Basically the blog boils down to this.

When making a class for WCF, DO NOT:

[DataContract]
class wxyz
{
        List<T> _var = new List<T>();

        [DataMember]
        public IList<T> Var
        {
            get { return _var; }
        }

// rest of your code...
}

DO this instead

[DataContract]
class wxyz
{
        List<T> _var;

	public wxyz() { Initialize(); }


	[OnDeserializing]
	private void OnDeserialize()
	{
	    Initialize();
	}


	private void Initialize()
	{
	    _var = new List<T>();
	}


        [DataMember]
        public IList<T> Var
        {
            get { return _var; }
        }

// rest of your code...
}

I guess to put it bluntly: the problem is that objects, generics and lists are not implicitly created during deserialization (and are thus null on serialzation). So you have to explicitly create them by using the [OnDeserialization] tag, which I guess is some sort of event trap. It worked for my situation, let me know if it works for yours.