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Asked: 2026-05-26T15:12:19+00:00

This is my Default.aspx + jQuery Script: <!DOCTYPE html PUBLIC -//W3C//DTD XHTML 1.0 Transitional//EN

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This is my Default.aspx + jQuery Script:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org
/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="Default.aspx.cs" 
Inherits="Sample001.Default" %>
<script src="jquery-1.6.4.min.js" type="text/javascript"></script>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
</head>
<body>
    <form id="form1" runat="server">
    <div>
        <table>
            <tr>
                <td>
        <asp:Label ID="masterlbl" Text="Master" runat="server" />
                </td>
                <td>
                    <span class="Mastercs">
                <asp:DropDownList ID="ddl1" runat="server">
                <asp:ListItem Text="Item1" Value="Item1" />
                <asp:ListItem Text="Item2" Value="Item2" />
                <asp:ListItem Text="Item3" Value="Item3" />
                <asp:ListItem Text="Item4" Value="Item4" />
                <asp:ListItem Text="Item5" Value="Item5" />
                </asp:DropDownList>
                    </span>
                </td>
                <td>
            <asp:Label ID="slavelbl" Text="Slave" runat="server" />
            </td>
                <td>
                    <span class="slavecs">
                    <asp:DropDownList ID="ddl2" runat="server" />
                    </span>
                </td>
            </tr>
        </table>
    </div>
    </form>
    <script type="text/javascript">
        $(document).ready(function () {
            $('span.Mastercs select').change(function () {
                $.ajax({
                    type: "POST",
                    url: 'MyHandler.ashx',
                    dataType: "text",
                    data: "ItemSelected=" + $('select#ddl1').val(),
                    async: true,
                    success: function (data) { Handler_Success(data); }
                });
            });
            function Handler_Success(data) {
                $('select#ddl2').empty();
                $.each(data, function (i, slaveValue) {
$('select#ddl2').append($('<option></option>')
.val(data.Value).html(data.Text));
                });
            }
        });
    </script>
</body>
</html>

The above code work correctly.
But I need to pass one more parameter, and there is a problem.
I try This Way and also the following code, but retrieve null value:

$.ajax({
    type: "POST",
    url: 'MyHandler.ashx',
    dataType: "text",
    data: '{"ItemSelected=" ' + $('select#ddl1').val() + ', "ID="' + 
    $('select#ddl1').attr('id') + ' }',
    async: true,
    success: function (data) { Handler_Success(data); }
    });
});

Where is the problem?

Edit:

I also need to use HttpHandler rather WebService or WebMethod

this is my HttpHandler:

public class SlaveValue {
    public string Value { get; set; }
    public string Text { get; set; }
    }

public class SlaveValueHandler : IHttpHandler {

    public bool IsReusable {
    get { return true; }
    }

        public void ProcessRequest(HttpContext context) {
            string valueSelected = context.Request["ItemSelected"];
            string id = context.Request["ID"];
            List<SlaveValue> slaveValues = new List<SlaveValue>();
            SlaveValue sv;
            sv = new SlaveValue();
            sv.Text = "SV1";
            sv.Value = valueSelected + id + "s1";
            slaveValues.Add(sv);
string responseText = Newtonsoft.Json.JsonConvert.SerializeObject(slaveValues);
context.Response.ContentType = "text/json";
context.Response.Write(responseText);
}
}

And My WebConfig:

<configuration>
    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <handlers>
            <add name="Slave Handler" verb="*" path="MyHandler.ashx" 
type="Sample001.SlaveValueHandler,Sample001" preCondition="integratedMode" />
        </handlers>
    </system.webServer>
    <system.web>
        <compilation debug="true" targetFramework="4.0" />
    </system.web>

</configuration>

Edit:

I Find it here:
CodeProject

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1 Answer

  1. Editorial Team

    There is another way – using json2.js

    var postdata = new Object();
postdata.parameter1 = <value>;
postdata.parameter2 = <value>; 

$.ajax({ 
type: "POST", 
url: 'MyHandler.ashx', 
dataType: "application/json", 
data: JSON.stringify(postdata), 
async: true, 
success: function (data) { Handler_Success(data); } 
}); 
});

    You are saved from formatting your JSON string everytime you add a new parameter. Make sure to read the it with the same name on the server side, else this wont work.

    JSON 2 is available here: https://github.com/douglascrockford/JSON-js/blob/master/json2.js

    Mark as answer if this worked for you

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