Using JQuery to call a WebMethod

Question

I am having trouble getting inside my Search WebMethod from my JQuery call. Maybe someone could help to point me in the right direction.

I also packed up everything into a zip file incase someone wants to check it out for a closer look.

http://www.filedropper.com/jsonexample

Thanks Ryan

    <%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>JSON Example</title>
    <script type="text/javascript" language="JavaScript" src="jquery-1.3.1.min.js"></script>

<script type="text/javascript" language="javascript">

function Search() {
    var search = $("#searchbox").val();
    var options = {
        type: "POST",
        url: "Default.aspx/Search",
        data: "{text:" + search + "}",
        contentType: "application/json; charset=utf-8",
        dataType: "json",
        success: function(msg) {
            alert('Success!');
        }
    };
    $.ajax(options);
}
</script>

</head>
<body>
    <form id="form1" runat="server">
        <input type="text" id="searchbox" size="40" />
        <a href="#" onclick="Search()" id="goSearch">Search</a>
        <br />        
        <div id="Load" />
    </form>
</body>
</html>

And here is the code behind for the default.aspx

 Imports System.Data
    Imports System.Web.Services
    Imports System.Web.Script.Serialization

    Partial Class _Default
        Inherits System.Web.UI.Page

        <WebMethod()> _
        Public Shared Function Search(ByVal text As String) As IEnumerable
            Return "test"
        End Function

    End Class

What do you mean getting inside your WebMethod, like not hitting a breakpoint? Why don't you just use the code that is emitted for you via MS Ajax PageMethods? Otherwise calling it via jQuery doesn't really save you anything. — Quintin Robinson, Feb 18 '09 at 22:30
I understand that there are a couple of other ways to access methods through javascript such as PageMethods. I also realize that this example doesnt do anything. But I made the simpliest non working version for everyone's help. I just am not able to get inside my breakpoint for the Search Method. — , Feb 18 '09 at 22:38
including you open/close script tags on the same line trucates your code. Please update your question and put a line break between the open and close script tags. — bendewey, Feb 19 '09 at 01:25

score 15 · Accepted Answer · answered Feb 18 '09 at 23:02

To solve a problem like this, the first thing to do is watch it in Firebug.

If you click the "Search" link and watch the POST request/response in Firebug's console, you'll see it's throwing a 500 server error: Invalid JSON Primitive.

The reason for that is because the key/value identifiers in your "data" JSON literal aren't quoted. Line 17 should be:

data: "{'text':'" + search + "'}",

Then, all will work as expected.

Note: The suggested data { test: search } will not work. If you provide jQuery with an actual JSON literal instead of a string, it will convert that into a key/value pair of test=search and POST that instead of the JSON. That will also cause an ASP.NET AJAX ScriptService or PageMethod to throw the Invalid JSON Primitive error.

That fixed it! Thanks Dave, I love your blog and the amazing stuff you write about. — , Feb 19 '09 at 13:49

score 6 · Answer 2 · answered Feb 18 '09 at 22:38

You need to do the following (C#):

The WebMethod must be public static
It must be decorated with the [WebMethod] attribute
You need a ScriptManager on your .aspx page
Set the ScriptManager's EnablePageMethods="true"

And here is some sample javascript:

$().ready(function() {
    $(yourDropDownList).change(LoadValues);
});


function LoadValues() {
    PageMethods.YourMethod(arg1, CallSuccess, CallFailed);
}

function CallFailed(result) {
    alert('AJAX Error:' + result.get_message());
}

function CallSuccess(result) {
    //do whatever you need with the result
}

I am using a shared method. The method that you are describing is the other type of way to access webmethods. I got my example based off http://encosia.com/2008/05/29/using-jquery-to-directly-call-aspnet-ajax-page-methods/ — , Feb 18 '09 at 22:45

Using JQuery to call a WebMethod

2 Answers2

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