Anonymous return in ASP.Net WebService

Question

I created a webservice function which returns an object (anonymous linq result)

    [WebMethod]
    [ScriptMethod(UseHttpGet = true, ResponseFormat = ResponseFormat.Json)]
    public object GetUser()
    {
        List<string> users = new List<string>
        {
            "Nora Aunor",
            "Pilita Corrales"
        };

        var result = users.Select(u => new
            {
                Name = u,
                Birthdate = DateTime.Now
            })
            .ToList();

        var retVal = new
        {
            Data = result,
            Count = result.Count
        };

        return retVal;
    }

if i use Fiddler to get the response, it returns ok with what data i expected

but if i use the browser, it just return an error

System.InvalidOperationException: There was an error generating the XML document. ---> System.InvalidOperationException: <>f__AnonymousType2`2[System.Collections.Generic.List`1[<>f__AnonymousType1`2[System.String,System.DateTime]],System.Int32] cannot be serialized because it does not have a parameterless constructor.
   at System.Xml.Serialization.TypeDesc.CheckSupported()
   at System.Xml.Serialization.TypeScope.GetTypeDesc(Type type, MemberInfo source, Boolean directReference, Boolean throwOnError)
   at System.Xml.Serialization.XmlSerializationWriter.CreateUnknownTypeException(Type type)
   at System.Xml.Serialization.XmlSerializationWriter.WriteTypedPrimitive(String name, String ns, Object o, Boolean xsiType)
   at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write1_Object(String n, String ns, Object o, Boolean isNullable, Boolean needType)
   at Microsoft.Xml.Serialization.GeneratedAssembly.XmlSerializationWriter1.Write3_anyType(Object o)
   at Microsoft.Xml.Serialization.GeneratedAssembly.ObjectSerializer1.Serialize(Object objectToSerialize, XmlSerializationWriter writer)
   at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
   --- End of inner exception stack trace ---
   at System.Xml.Serialization.XmlSerializer.Serialize(XmlWriter xmlWriter, Object o, XmlSerializerNamespaces namespaces, String encodingStyle, String id)
   at System.Xml.Serialization.XmlSerializer.Serialize(TextWriter textWriter, Object o, XmlSerializerNamespaces namespaces)
   at System.Web.Services.Protocols.XmlReturnWriter.Write(HttpResponse response, Stream outputStream, Object returnValue)
   at System.Web.Services.Protocols.HttpServerProtocol.WriteReturns(Object[] returnValues, Stream outputStream)
   at System.Web.Services.Protocols.WebServiceHandler.WriteReturns(Object[] returnValues)
   at System.Web.Services.Protocols.WebServiceHandler.Invoke()

Question: how to show the structure + data of the anonymous method into json that will show in the browser like this

{
    "d": {
        "Data": [{
            "Name": "Nora Aunor",
            "Birthdate": "\/Date(1393578983512)\/"
        },
        {
            "Name": "Pilita Corrales",
            "Birthdate": "\/Date(1393578983512)\/"
        }],
        "Count": 2
    }
}

or the default XML result.

Thanks in advance

Answer 1

Error is a Content-Type header. Try to remove it from request in Fiddler and you'll see same exception. Browser doesn't send Content-Type: application/json it and your webserice tries to return XML serialized object and fails. This is generally ASP.NET security policy. Check this url for more information