JSON response returned with \ before quotes…why?

Question

I have a REST-service that returns JSON. But the JSON response returned with \ before quotes (escape character)....I need those escapre slashes removed!

This is an example response to show what is happening:

"[{\"Id\":\"0\",\"FirstName\":\"0firstname\",\"LastName\":\"0 lastname\"},{\"Id\":\"1\",\"FirstName\":\"1firstname\",\"LastName\":\"1 lastname\"},{\"Id\":\"2\",\"FirstName\":\"2firstname\",\"LastName\":\"2 lastname\"},{\"Id\":\"3\",\"FirstName\":\"3firstname\",\"LastName\":\"3 lastname\"},{\"Id\":\"4\",\"FirstName\":\"4firstname\",\"LastName\":\"4 lastname\"},{\"Id\":\"5\",\"FirstName\":\"5firstname\",\"LastName\":\"5 lastname\"},{\"Id\":\"6\",\"FirstName\":\"6firstname\",\"LastName\":\"6 lastname\"},{\"Id\":\"7\",\"FirstName\":\"7firstname\",\"LastName\":\"7 lastname\"},{\"Id\":\"8\",\"FirstName\":\"8firstname\",\"LastName\":\"8 lastname\"},{\"Id\":\"9\",\"FirstName\":\"9firstname\",\"LastName\":\"9 lastname\"},{\"Id\":\"10\",\"FirstName\":\"10firstname\",\"LastName\":\"10 lastname\"}]"

The JSON is parsed by Layar (http://layar.pbworks.com/w/page/28473583/GetPOIs-Request%20and%20Response%20Examples), so I cant influence the parsing and they dont allow these escape characters.

Here's my code:

**RestServiceImpl.vb

Imports System.ServiceModel
Imports System.ServiceModel.Web
Imports System.IO
Imports System.ServiceModel.Activation
Imports System.Web.Script.Serialization
Imports System.Collections.Generic

Namespace RestService

Public Class Employee
    Public Property Id() As String
        Get
            Return m_Id
        End Get
        Set(value As String)
            m_Id = Value
        End Set
    End Property
    Private m_Id As String
    Public Property FirstName() As String
        Get
            Return m_FirstName
        End Get
        Set(value As String)
            m_FirstName = Value
        End Set
    End Property
    Private m_FirstName As String
    Public Property LastName() As String
        Get
            Return m_LastName
        End Get
        Set(value As String)
            m_LastName = Value
        End Set
    End Property
    Private m_LastName As String
End Class

<AspNetCompatibilityRequirements(RequirementsMode:=AspNetCompatibilityRequirementsMode.Allowed)> _
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

        Dim json As New JavaScriptSerializer()
        Dim l As New List(Of Employee)

        Dim e As Employee
        For i As Integer = 0 To 10
            e = New Employee
            e.Id = i.ToString
            e.FirstName = i.ToString + "firstname"
            e.LastName = i.ToString + " lastname"
            l.Add(e)
        Next i

        Dim jsonMessage As String = json.Serialize(l.ToArray())
        Return jsonMessage

    End Function

End Class



End Namespace

**IRestServiceImpl.vb

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

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

Answer 1

Turns out it's BAD to manually serialize json like this: json.Serialize(l.ToArray()). I was reading this here: http://encosia.com/asp-net-web-services-mistake-manual-json-serialization/ So, what I did is just return the list of employees and now its all good!

Answer 2

Those slashes are escape characters for the quotes, which it is doing correctly because the return type is String. You could change your JSONData to return As List(Of Employee)...

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

            Dim json As New JavaScriptSerializer()
            Dim l As New List(Of Employee)

            Dim e As Employee
            For i As Integer = 0 To 10
                e = New Employee
                e.Id = i.ToString
                e.FirstName = i.ToString + "firstname"
                e.LastName = i.ToString + " lastname"
                l.Add(e)
            Next i


            Return json.Serialize(l.ToArray())

End Function