asmx won't return JSON - json

Question

I've completely rewritten this old asmx service function but I still can't get it to return JSON. It returns XML, even if I use ajax() and set the datatype and contenttype to json. I'm trying to use this function with Jquery dataTables. And I know there are tons of questions like this but all of them I've found are C# and I was unable to adapt them.
up-to-date pastebin of full asmx file: http://pastebin.com/swXKqgd4
new code
<WebMethod()> _
<WebGet(ResponseFormat:=WebMessageFormat.Json)> _
Public Function rptPendingServerRequests() As Generic.List(Of request)
Dim _conn As SqlConnection = New SqlConnection(connectionString)
Dim _dr As SqlDataReader
Dim Sql As String = String.Empty
Sql += "<My query here>"
Try
Dim _cmd As SqlCommand = New SqlCommand(Sql, _conn)
_conn.Open()
_dr = _cmd.ExecuteReader(CommandBehavior.CloseConnection)
If _dr.HasRows Then
Dim s As request
Dim c As New Generic.List(Of request)
While _dr.Read
s = New request
With s
.requestID = _dr("request_id")
.status = _dr("status")
.requester = _dr("req_by_user_id")
.assignee = _dr("user_id")
.nextAction = _dr("description")
End With
c.Add(s)
End While
Return c
End If
Catch ex As Exception
MsgBox(ex.Message)
Finally
_conn.Close()
End Try
End Function
New class
<Serializable()> _
Public Class request
Private _requestID As Integer
Public Property requestID() As Integer
Get
Return _requestID
End Get
Set(ByVal value As Integer)
_requestID = value
End Set
End Property
Private _requester As String
Public Property requester() As String
Get
Return _requester
End Get
Set(ByVal value As String)
_requester = value
End Set
End Property
Private _requestDate As Date
Public Property requestDate() As Date
Get
Return _requestDate
End Get
Set(ByVal value As Date)
_requestDate = value
End Set
End Property
Private _status As Integer
Public Property status() As Integer
Get
Return _status
End Get
Set(ByVal value As Integer)
_status = value
End Set
End Property
Private _assignee As String
Public Property assignee() As String
Get
Return _assignee
End Get
Set(ByVal value As String)
_assignee = value
End Set
End Property
Private _nextAction As String
Public Property nextAction() As String
Get
Return _nextAction
End Get
Set(ByVal value As String)
_nextAction = value
End Set
End Property
End Class
Original Code
<WebMethod()> _
<WebGet(ResponseFormat:=WebMessageFormat.Json)> _
Public Function rptPendingServerRequestsOld() As DataSet
Dim connection As SqlConnection
Dim command As SqlCommand
Dim adapter As New SqlDataAdapter
Dim ds As New DataSet
Dim sql As String
sql = ""
sql += "<MY query here>"
connection = New SqlConnection(connectionString)
Try
connection.Open()
command = New SqlCommand(sql, connection)
adapter.SelectCommand = command
adapter.Fill(ds)
adapter.Dispose()
command.Dispose()
connection.Close()
Return ds
Catch ex As Exception
End Try
End Function
Client
$('#report').dataTable({
"bProcessing": true,
"sAjaxSource": 'reportdata.asmx/rptPendingServerRequests'
});

Answer 1

Since you're calling this method from JS instead of
<WebGet(ResponseFormat:=WebMessageFormat.Json)>
use
<ScriptMethod(ResponseFormat:=ResponseFormat.Json)>
attribute. Also don't forget to mark your WebService class with
<ScriptService()>
attribute.

Answer 2

Change this line.
Public Function rptPendingServerRequests() As Generic.List(Of request)
to
Public Function rptPendingServerRequests() As String.