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[System.Web.Services.WebMethod] return object value using json or another convient class

Answer 1

+1 A:

It's an AJAX call. You cannot write:

var s = PageMethods.ShowMessage();

and expect to use the s variable immediately because the call is asynchronous (it returns immediately but the result is available only later after the server responds). You need to use the callback. Here's a full working example:

<%@ Page Language="C#" %>
<%@ Import Namespace="System.Web.Services" %>
<%@ Import Namespace="System.Web.Script.Services" %>
<script type="text/C#" runat="server">
    [WebMethod]
    [ScriptMethod(ResponseFormat = ResponseFormat.Json)]
    public static string ShowMessage()
    {
        return "Okay Buddy" + DateTime.Today.ToLongDateString();
    }
</script>
<!DOCTYPE html>
<html>
<head>
    <title>Test</title>
    <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
    <script type="text/javascript">
        function CallMe() {
            // call server side method
            PageMethods.ShowMessage(function (result) {
                alert(result);
            });
        }

        (function() {
            var status = true;
            var fetchService = function () {
                if (status) {
                    CallMe();
                    status = false;
                }
                setTimeout(fetchService, 5000);
                status = true;
            }

            window.onload = fetchService;
        }());
    </script>
</head>
<body>
    <form id="form1" runat="server">
        <asp:ScriptManager ID="scm" runat="server" EnablePageMethods="true" />
    </form>
</body>
</html>

Also notice that you should not use JavaScriptSerializer manually. It is used internally by PageMethods. In your ShowMessage method you could also return complex objects.

If the method had for example two arguments you would pass them before the success and error callbacks:

PageMethods.ShowMessage('param1', 'param2', onSucceed, onError);

Darin Dimitrov 2010-09-17 07:26:52

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[System.Web.Services.WebMethod] return object value using json or another convient class

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