RESTful C# service not responding in json

Question

I have a RESTful service that has been around for a short while, returning json whenever its methods are called. Just lately i've added a new method, written in exactly the same manner as the others, but it only responds in xml.

Here are the existing method interface definitions:

[ServiceContract]
public interface IAccess
{

    [OperationContract]
    [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "GetRunList?username={username}&FromRun={FromRun}&ToRun={ToRun}&Project={Project}")]
    List<RunInfo> GetRunList(string username, int FromRun, int ToRun, string Project = null);

    [OperationContract]
    [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "GetPressureTap?RunNumber={RunNumber}")]
    ServicePressureTapMap GetPressureTap(int RunNumber);

    [OperationContract]
    [WebInvoke(Method = "GET", ResponseFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "GetPressureTapByAttitude?RunNumber={RunNumber}&FRH={FRH}&RRH={RRH}&Yaw={Yaw}&Steer={Steer}&Roll={Roll}&Exhaust={Exhaust}")]
    List<ServiceAttitudePressureTap> GetPressureTapByAttitude(int RunNumber, decimal FRH, decimal RRH, decimal Yaw, decimal Steer, decimal Roll, decimal Exhaust);

    [OperationContract]
    [WebInvoke(Method = "GET", RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "GetPresTapImage?RunNumber={RunNumber}&MapGuid={MapGuid}&MapName={MapName}&Version={Version}")]
    Stream GetPresTapImage(int RunNumber, string MapGuid, string MapName, int Version);

}

and all I've done is added the following new method to the bottom:

    [OperationContract]
    [WebInvoke(Method = "GET", RequestFormat = WebMessageFormat.Json, BodyStyle = WebMessageBodyStyle.Wrapped, UriTemplate = "GetRunConfigs?RunNumber={RunNumber}")]
    List<ServiceRunConfig> GetRunConfigs(int RunNumber);

The returned classes have all been declared in the same manner. Only the new method comes back as XML. Have I missed something glaringly obvious?

Answer 1

It turns out, after much searching that I needed to add this:

<endpointBehaviors>
  <behavior name="endpointBehavior">
    <enableWebScript />
    <webHttp defaultBodyStyle="Wrapped" defaultOutgoingResponseFormat="Json" />
  </behavior>
</endpointBehaviors>

to my web.config, despite having the WebInvoke line in the Interface that does eactly the same thing. Go figure...