How to return Faults in JSON from AJAX Enabled WCF Service? - ajax

Question

I have an AJAX-enabled WCF service (with enableWebScript in the behavior) that has a ValidationFault which I created.
Here's the service:
[ServiceContract]
public interface ICoreWCF
{
/// <summary>
/// Saves the Customer.
/// </summary>
[OperationContract]
[WebInvoke(BodyStyle = WebMessageBodyStyle.WrappedRequest)]
[FaultContract(typeof(ValidationFault))]
void Customer_Save(Customer customer);
}
Here's the fault:
[DataContract]
public class ValidationFault
{
[DataMember(Name = "success")]
public bool Success { get; set; }
[DataMember(Name = "msg")]
public string ValidationMessage { get; set; }
[DataMember(Name = "errors")]
public Dictionary<string, string> Errors { get; set; }
}
I would like to send this fault back to the client javascript.
The problem is that my custom fault's DataMembers are ignored and a general exception is returned.
How can I send the errors collection to the client?
I already tried writing my own IErrorHandler similar to this, such that it uses Exception Handling Application Block to convert an exception to a fault, and then the IErrorHandler serializes the resulting fault. But it appears that the JsonErrorHandler of the WebScriptingEnablingBehavior is not dealing well with the resulting Message object.
Thanks.

Answer 1

If you have implemented IErrorHandler and associated it to service using using custom behavior inherited from WebHttpBehavior as sighted by link then perhaps you should try adding default request/response format etc. For example,
private class CustomWebScriptBehavior : WebHttpBehavior
{
protected override void AddServerErrorHandlers(ServiceEndpoint endpoint,
System.ServiceModel.Dispatcher.EndpointDispatcher endpointDispatcher)
{
// clear current error handlers
endpointDispatcher.ChannelDispatcher.ErrorHandlers.Clear();
// add our error handler
endpointDispatcher.ChannelDispatcher.ErrorHandlers.Add(
new ErrorHandler(true));
}
private WebMessageFormat _requestFormat;
private WebMessageFormat _responseFormat;
public CustomWebScriptBehavior()
{
_requestFormat = _responseFormat = WebMessageFormat.Json;
}
public override bool AutomaticFormatSelectionEnabled
{
get { return false; }
set { throw new NotSupportedException(); }
}
public override WebMessageBodyStyle DefaultBodyStyle
{
get { return WebMessageBodyStyle.WrappedRequest; }
set { throw new NotSupportedException(); }
}
public override WebMessageFormat DefaultOutgoingRequestFormat
{
get { return _requestFormat; }
set { _requestFormat = value; }
}
public override WebMessageFormat DefaultOutgoingResponseFormat
{
get { return _responseFormat; }
set { _responseFormat = value; }
}
}
This will eliminate the need to specify WebInvoke attribute for each method.

Answer 2

in webinvoke you can add RequestFormat=WebMessageFormat.Json, ResponseFormat=WebMessageFormat.Json
try it