wCFService returning xml instead of expected json - asp.net

Question

I was trying to make a webservice call to return json formatted data to populated a grid control. It was not working and after using fiddler and firebug to monitor the call I see the data wrapped as xml. I tried to different calls; one makes a call to mongodb and the result is a simply collection and the other is data from another endpoint that is json format. I have the webservice set up as follows:
Imports System.Web.Services
Imports System.Web.Services.Protocols
Imports System.ComponentModel
Imports System.Web.Script.Services
Imports System.Web.Script.Serialization
Imports System.Net
Imports System.IO
Imports System.Xml
Imports Newtonsoft.Json
Imports System.ServiceModel
Imports MongoDB.Driver
Imports MongoDB.Bson
<System.Web.Script.Services.ScriptService()> _
<System.Web.Services.WebServiceBinding(ConformsTo:=WsiProfiles.BasicProfile1_1)> _
<ServiceBehaviorAttribute(IncludeExceptionDetailInFaults:=True)>
<ToolboxItem(False)> _
Public Class WebService1
Inherits System.Web.Services.WebService
Private mongo As MongoServer = MongoServer.Create()
Private Function convertToJson(ByVal username As String)
Dim product As New splnkObject()
product.userName = username
Dim jsonT As String = JsonConvert.SerializeObject(product)
Return jsonT
End Function
<WebMethod()> _
<ScriptMethod(UseHttpGet:=True,
XmlSerializeString:=False, ResponseFormat:=ResponseFormat.Json)> _
Public Function getDBData() As String
Dim response As String = String.Empty
mongo.Connect()
Dim db = mongo.GetDatabase("nodetest1")
Using mongo.RequestStart(db)
Dim collection = db.GetCollection(Of BsonDocument)("usercollection").FindAll()
response = collection.Collection.ToString
response = "{""d"":" + response + "}"
Return collection.ToArray.ToJson
End Using
End Function
This is the response captured in fiddler and the json tab says invalid json in body:
string [ xmlns=http://tempuri.org/ ]
[{ "_id" : ObjectId("52d2f2b3c60804b25bc5d2ca"), "username" : "testuser1",
"email" : "testuser1#testdomain.com" },
{ "_id" : ObjectId("52d2f2f9c60804b25bc5d2cb"), "username" : "testuser2",
"email" : "testuser2#testdomain.com" },
{ "_id" : ObjectId("52d2f2f9c60804b25bc5d2cc"), "username" : "testuser3",
"email" : "testuser3#testdomain.com" }]
My webconfig file as follows:
<?xml version="1.0"?>
<configuration>
<appSettings>
<add key="connectionString2" value="Server=localhost:27017"/>
</appSettings>
<connectionStrings>
<system.web>
<authentication mode="None" />
<authorization>
<allow users="?" />
</authorization>
<compilation debug="true" strict="false" explicit="true" targetFramework="4.0">
<assemblies>
<add assembly="System.Data.Linq, Version=4.0.0.0,
Culture=neutral, PublicKeyToken=B77A5C561934E089"/>
</assemblies>
</compilation>
<httpHandlers>
<remove verb="*" path="*.asmx"/>
<add verb="*" path="*.asmx"
type="System.Web.Script.Services.ScriptHandlerFactory" validate="false"/>
</httpHandlers>
<webServices>
<protocols>
<add name="HttpGet"/>
<add name="HttpPost"/>
</protocols>
</webServices>
</system.web>
<system.webServer>
<modules runAllManagedModulesForAllRequests="true"/>
</system.webServer>
<system.serviceModel>
<serviceHostingEnvironment aspNetCompatibilityEnabled="false"
multipleSiteBindingsEnabled="true" />
<services>
<service name="WbTest.Service1">
<endpoint address="" behaviorConfiguration="WbTest.Service1AspNetAjaxBehavior"
binding="webHttpBinding" contract="WbTest.IService1" />
</service>
</services>
<behaviors>
<endpointBehaviors>
<behavior name="WebBehavior">
<webHttp />
<enableWebScript />
</behavior>
<behavior name="WbTest.Service1AspNetAjaxBehavior">
<enableWebScript />
</behavior>
</endpointBehaviors>
<serviceBehaviors>
<behavior name="">
<serviceDebug includeExceptionDetailInFaults="false" />
</behavior>
</serviceBehaviors>
</behaviors>
<bindings />
<client />
</system.serviceModel>
</configuration>
The javascript call:
var myStore = new Ext.data.Store({
model: 'User',
proxy: {
type: 'ajax',
url: 'WCFService/WebService1.asmx/getDBData',
contentType: 'application/json; charset=utf-8',
reader: {
type: 'json',
root: '_id'
}
}
});
myStore.load();
Please could someone take a look and identify where the issue is.

Answer 1

I'm not going to say this is the "right" way, however, one option would be to not specify a return type on the method and write directly to the response(HttpContext.Current.Response) object.
<WebMethod()> _
Public Sub getDBData()
Dim response As String = String.Empty
mongo.Connect()
Dim db = mongo.GetDatabase("nodetest1")
Using mongo.RequestStart(db)
Dim collection = db.GetCollection(Of BsonDocument)("usercollection").FindAll()
response = collection.Collection.ToString
response = "{""d"":" + response + "}"
Dim responseJson as String
responseJson = Collection.ToArray.ToJson
HttpContext.Current.Response.Write(responseJson)
End Using
End Sub
Additionally, If you are going to use Newtonsoft to manipulate objects, i find this method works well.
I should note, that asmx web services are legacy and the newer technology is wcf.