Question

I am working on a WCF webservice.
I need to create a Post service that returns a Json stringhe service is declared as follows:

[WebInvoke(UriTemplate = "GetMatAnalysis",  ResponseFormat = WebMessageFormat.Json, 
                                                RequestFormat = WebMessageFormat.Json, 
                                                BodyStyle = WebMessageBodyStyle.WrappedRequest, 
                                                Method = "POST")]
string GetMatAnalysis(Stream image);

in this message I am serializing object with using JavaScriptSerializer().Serialize()
and then return it.

however when I get the responce there is a extra Double-Quote at the start and at the end of the string. For example I am getting: "{"results" : 10 }" instead of {"results" : 10 }

I tried to change the return type to System.ServiceModel.Channels.Message I get this error:

An ExceptionDetail, likely created by IncludeExceptionDetailInFaults=true, whose value is:
System.InvalidOperationException: An exception was thrown in a call to a WSDL export extension: System.ServiceModel.Description.DataContractSerializerOperationBehavior contract: http://tempuri.org/:IMyWebServices ----> System.InvalidOperationException: The operation 'GetMatAnalysis' could not be loaded because it has a parameter or return type of type System.ServiceModel.Channels.Message or a type that has MessageContractAttribute and other parameters of different types. When using System.ServiceModel.Channels.Message or types with MessageContractAttribute, the method must not use any other types of parameters.

How can I make it return a json string without the double quotes?

Additional information:

When I use GET request like this:

[OperationContract(Name = "Messages")]
[WebGet(UriTemplate = "Messages/GetMessage", ResponseFormat = WebMessageFormat.Json)]
Message GetAdvertisment();

The return type is message and it works correctly. The Json string received is correct.

Any help is greatly appreciated.
Thank you

Answer 1

Since ResponseFormat = WebMessageFormat.Json, WCF service serializes your returned object as Json. You also use JavaScriptSerializer().Serialize() and you get double serialization.