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c#jsonwcfpost
Y2theZ
Y2theZ

Reputation: 10402

WebInvoke return Json string with extra quotes

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

Upvotes: 1

Views: 2816

Answers (2)

Davatar
Davatar

Reputation: 156

Return a Stream instead of a string and set the content type of the outgoing response to "application/json; chatset=utf-8". This will return everything properly.

Interface:

[ServiceContract]
interface ITestService
{        
    [OperationContract]
    [WebInvoke(Method = "POST", ResponseFormat = WebMessageFormat.Json, UriTemplate = "/GetMatAnalysis")]
    Stream GetMatAnalysis(Stream image);
}

Service:

[ServiceBehavior(InstanceContextMode = InstanceContextMode.PerCall)]
public class TestService : ITestService
{
    public Stream GetMatAnalysis(Stream image)
    {
        MatAnalysisResult matAnalysis = new MatAnalysisResult { results = 10 };

        string result = JsonConvert.SerializeObject(matAnalysis);
        WebOperationContext.Current.OutgoingResponse.ContentType = "application/json; charset=utf-8";

        return new MemoryStream(Encoding.UTF8.GetBytes(result));
    }
}

The result will be:

{"results":10}

Upvotes: 0

L.B
L.B

Reputation: 116108

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

Upvotes: 1

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