Question

Found a great article about using jQuery to consume a codebehind WebMethod. I am trying to apply it on my website. But I keep getting the following error though I ensured that the param names are the same.

        $(".StreamLike").live("mouseover", function () {
            var Id = $(this).parent().parent().find(".StreamIndex").html();
            alert(Id);
            $.ajax({
                type: 'POST',
                url: 'Default.aspx/GetLikes',
                data: { "Id": Id },
                contentType: 'application/json; charset=utf-8',
                dataType: 'json',
                success: LikesSuccess,
                error: LikesError
            });
        }); 

        function LikesSuccess(result, userContext, methodName) {
            for (var i in result) {
                alert(result[i]); 
            }

WebMethod:

[WebMethod]
public static string[] GetLikes(int Id)
{
    List<Like> Likes = Like.GetById(Id, false);
    string[] Senders = new string[Likes.Count];
    for (int i = 0; i < Likes.Count; i++)
    {
        Senders[i] = Likes[i].Sender;            
    }
    return Senders;
}

The full error message is as follows:

{“Message”:”Invalid JSON primitive: Id.”,”StackTrace”:” at
System.Web.Script.Serialization.JavaScriptObjectDeserializer.DeserializePrimitiveObject()\r\n
at
System.Web.Script.Serialization.JavaScriptObjectDeserializer.DeserializeInternal(Int32
depth)\r\n at
System.Web.Script.Serialization.JavaScriptObjectDeserializer.BasicDeserialize(String
input, Int32 depthLimit, JavaScriptSerializer serializer)\r\n at
System.Web.Script.Serialization.JavaScriptSerializer.Deserialize(JavaScriptSerializer
serializer, String input, Type type, Int32 depthLimit)\r\n at
System.Web.Script.Serialization.JavaScriptSerializer.Deserialize[T](String
input)\r\n at
System.Web.Script.Services.RestHandler.GetRawParamsFromPostRequest(HttpContext
context, JavaScriptSerializer serializer)\r\n at
System.Web.Script.Services.RestHandler.GetRawParams(WebServiceMethodData
methodData, HttpContext context)\r\n at
System.Web.Script.Services.RestHandler.ExecuteWebServiceCall(HttpContext
context, WebServiceMethodData
methodData)”,”ExceptionType”:”System.ArgumentException”}

It’s always hitting LikesError…

Answer 1

Try this…

data: JSON.stringify({ “Id”: Id })

The post is turning your “Id” object into name/value pairs. e.g. Id=12345. You have to stringify the object first.