return raw JSON string without escape characters

Question

I was checking this post: Returning raw json (string) in wcf. I think Im running into somewhat the same problem I have a rest service that returnS JSON, see the code below:

IRestServiceImpl.vb

Imports System.ServiceModel
Imports System.ServiceModel.Web

Namespace RestService
' NOTE: You can use the "Rename" command on the context menu to change the interface name "IRestServiceImpl" in both code and config file together.
<ServiceContract()> _
Public Interface IRestServiceImpl
    <OperationContract()> _
    <WebInvoke(Method:="GET", ResponseFormat:=WebMessageFormat.Xml, BodyStyle:=WebMessageBodyStyle.Wrapped, UriTemplate:="xml/{id}")> _
    Function XMLData(ByVal id As String) As String


    'WebMessageBodyStyle.Bare WAS WebMessageBodyStyle.wrapped
    <OperationContract()> _
    <WebInvoke(Method:="GET", ResponseFormat:=WebMessageFormat.Json, BodyStyle:=WebMessageBodyStyle.Wrapped, UriTemplate:="api/objects/json/?lat={lat}&lon={lon}&radius={radius}&cat={cat}")> _
    Function JSONData(ByVal lat As String, ByVal lon As String, ByVal radius As String, ByVal cat As String) As String
    'radius in meters


End Interface
End Namespace

RestServiceImpl.vb

Namespace RestService
Public Class RestServiceImpl
    Implements IRestServiceImpl


    Public Function XMLData(ByVal id As String) As String _
        Implements IRestServiceImpl.XMLData

        Return "XML You requested product " & id

    End Function

    Public Function JSONData(ByVal lat As String, ByVal lng As String, ByVal d As String, ByVal cat As String) As String _
        Implements IRestServiceImpl.JSONData

        'returns the results JSON in format

        'Return "JSON lat=" + lat + " lng=" + lng + " d=" + d + " cat=" + cat
        Dim sBuilder As New StringBuilder

        sBuilder.Append("{""hotspots"": [")
        sBuilder.Append("{""id"": ""test_1"",")
        sBuilder.Append("""anchor"": { ""geolocation"": { ""lat"": 52.3729, ""lon"": 4.93 } },  ")
        sBuilder.Append("""text"": {")
        sBuilder.Append("""title"": ""The Layar Office"", ")
        sBuilder.Append("""description"": ""The Location of the Layar Office"", ")
        sBuilder.Append("""footnote"": ""Powered by Layar"" },")
        sBuilder.Append("""imageURL"": ""http:\/\/custom.layar.nl\/layarimage.jpeg"",")
        sBuilder.Append("}")
        sBuilder.Append("],")
        sBuilder.Append("""layer"": ""mytest"",")
        sBuilder.Append("""errorString"": ""ok"", ")
        sBuilder.Append("""errorCode"": 0")
        sBuilder.Append("} ")

        Return sBuilder.ToString

    End Function

End Class
End Namespace

Based on the above code I get this response:

Which gives me this response in Chrome browser: {"JSONDataResult":"{\"hotspots\": [{\"id\": \"test_1\",\"anchor\": { \"geolocation\": { \"lat\": 52.3729, \"lon\": 4.93 } }, \"text\": {\"title\": \"The Layar Office\", \"description\": \"The Location of the Layar Office\", \"footnote\": \"Powered by Layar\" },\"imageURL\": \"http:\/\/custom.layar.nl\/layarimage.jpeg\",}],\"layer\": \"mytest\",\"errorString\": \"ok\", \"errorCode\": 0} "}

I know think the backslashes are in my response because of the issue described in the other thread (since Im using WebMessageFormat.Json).

But Im unsure how to implement the code samples that were provided on http://blogs.msdn.com/b/carlosfigueira/archive/2008/04/17/wcf-raw-programming-model-web.aspx, http://msdn.microsoft.com/en-us/library/ms789010.aspx and http://msdn.microsoft.com/en-us/library/cc681221(VS.90).aspx

I now changed my Irestserviceimpl.vb to:

Imports System.ServiceModel
Imports System.ServiceModel.Web
Imports System.IO

Namespace RestService
' NOTE: You can use the "Rename" command on the context menu to change the interface name "IRestServiceImpl" in both code and config file together.
<ServiceContract()> _
Public Interface IRestServiceImpl
    <OperationContract()> _
    <WebInvoke(Method:="GET", ResponseFormat:=WebMessageFormat.Xml, BodyStyle:=WebMessageBodyStyle.Wrapped, UriTemplate:="xml/{id}")> _
    Function XMLData(ByVal id As String) As String


    'WebMessageBodyStyle.Bare WAS WebMessageBodyStyle.wrapped
    <OperationContract()> _
    <WebInvoke(Method:="GET", ResponseFormat:=WebMessageFormat.Json, BodyStyle:=WebMessageBodyStyle.Bare, UriTemplate:="api/objects/json/?lat={lat}&lon={lon}&radius={radius}&cat={cat}")> _
    Function JSONData(ByVal lat As String, ByVal lon As String, ByVal radius As String, ByVal cat As String) As String
    'radius in meters
End Interface


Public Class RawService
    <OperationContract(), WebGet()> _
    Public Function GetValue() As System.IO.Stream
        Dim result As String = "Hello world"
        Dim resultBytes As Byte() = Encoding.UTF8.GetBytes(result)
        WebOperationContext.Current.OutgoingResponse.ContentType = "text/plain"
        Return New MemoryStream(resultBytes)
    End Function
End Class

End Namespace

But am still unsure how to call the url or where to place which code exactly...if anyone could help me get started here?

Thanks!

Answer 1

Your function is creating one massive string, which when it gets converted to Json is creating a JSON element(is that the right word?) with only one attribute "JSONDataResult" which has a single value = the string you made (with all those quote marks now escaped).

The way you are doing it looks like quite hard work! Have you tried using the WCFWebApi? It's easy to implement and makes it very easy to return JSON or XML (and handles the de-serialization for you)