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MultiSelect Dropdown in ASP.NET

, 28 Jan 2010 CPOL
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Easy way to do multi select values in ASP.NET.


In this article, I will show you a different way of doing a multi-select in an ASP.nET page. I will keep this article short and sweet so you can just use the code in your applications.

Using the code

We are going to put our CheckBoxList ASP.NET control inside an HTML div object. I have also added code to support changing the background color of the selected row.

<%@ Page Language="C#" AutoEventWireup="true" 
  CodeFile="Default.aspx.cs" Inherits="_Default" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 

<html xmlns="">
<style type="text/css">
    height: 120px;
    width: 200px;
    padding: 5px;
    overflow: auto;
    border: 1px solid #ccc;

    FONT-SIZE: 11px;
    FONT-FAMILY: tahoma,sans-serif

<script language="javascript">

var color = 'White'; 

function changeColor(obj) 
    var rowObject = getParentRow(obj); 
    var parentTable = 

    if(color == '') 
        color = getRowColor(); 

    { = '#A3B1D8'; 
    { = color; 
        color = 'White'; 

    // private method
    function getRowColor() 
        if( == 'White')
        else return; 

// This method returns the parent row of the object
function getParentRow(obj) 
        obj = obj.parentElement; 
    while(obj.tagName != "TR") 
    return obj; 

function TurnCheckBoixGridView(id)
    var frm = document.forms[0];

    for (i=0;i<frm.elements.length;i++)
        if (frm.elements[i].type == "checkbox" && 
            frm.elements[i].id.indexOf("<%= chkList.ClientID %>") == 0)
            frm.elements[i].checked = 

function SelectAll(id)
    var parentTable = document.getElementById("<%=chkList.ClientID%>"); 
    var color

    if (document.getElementById(id).checked)
        color = '#A3B1D8'
        color = 'White'

    for (i=0;i<parentTable.rows.length;i++)
        parentTable.rows[i].style.backgroundColor = color;

<head runat="server">
<form id="form1" runat="server">
<div class="scroll_checkboxes">
<asp:CheckBoxList Width="180px" ID="chkList" 
  runat="server" CssClass="FormText" 
  RepeatDirection="Vertical" RepeatColumns="1" 
  BorderWidth="0" Datafield="description" 
<asp:ListItem id="text1" Value="Select me 1" 
<asp:ListItem id="text2" Value="Select me 2" 
<asp:ListItem id="text3" Value="Select me 3" 
<asp:ListItem id="text4" Value="Select me 4" 
<asp:ListItem id="text5" Value="Select me 5" 
<asp:ListItem id="text6" Value="Select me 6" 
<asp:ListItem id="text7" Value="Select me 7" 
<asp:ListItem id="text8" Value="Select me 8" 
<asp:ListItem id="text9" Value="Select me 9" 
<asp:ListItem id="text10" Value="Select me 10" 
<asp:ListItem id="text11" Value="Select me 11" 
<asp:ListItem id="text12" Value="Select me 12" 
<asp:ListItem id="text13" Value="Select me 13" 

If you would need to load this list from a database, then you can easily bind the CheckBoxList to a DataSource object.

To add the JavaScript call to change the color, just use text1.Attributes.Add("onclick", "changeColor(this)"); in the code-behind for each ListItem control (you would need to use a loop).

Highlight the row in a GridView using the same Javascript code

You can use the same JavaScript for highlighting a row in a GridView; for example, let's say, you have a GridView with an ItemTemplate that has a CheckBox.

Adding onclick="changeColor(this)" to the checkbox will do the trick.

<ItemTemplate >
  <asp:CheckBox ID="chkSelect" runat="server" 
     Width = "24px" Visible = "true" 
     onclick="changeColor(this)" EnableViewState="True" />
  <asp:Label ID="HiddenShipmentID" runat="server" 
     visible = "false" 
     Text = '<%# Eval("shipment_id") %>'></asp:Label>

All you have to do is change the JavaScript to use the name of the GridView:

var parentTable = document.getElementById("<%=chkList.ClientID%>");

Change that to:

var parentTable = document.getElementById("<%=GridViewName.ClientID%>");

And that's all.

I hope you enjoyed this little trick. If you liked this idea, feel free to vote.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


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Comments and Discussions

Questionadd textbox in this control PinmemberMember 1075349317-Apr-14 20:55 
QuestionCan u make this control usable in gridview Pinmembercooldiv4u11-Jun-13 1:00 
QuestionYou really think its a DropDrown!?????? PinmemberAliTopoli4-May-12 22:43 
AnswerRe: You really think its a DropDrown!?????? Pinmemberrperetz5-May-12 4:25 
QuestionCan you add searchable feature for this control Pinmemberraj chitty25-Apr-12 4:28 
QuestionNot a Drop down PinmemberDov Miller15-Mar-12 1:29 
GeneralMulti-Select Drop Down List in ASP.NET PinmemberRichard Xiong11-Aug-10 15:17 
GeneralDesign View error in VS 2005 PinmemberTonyOldskhl25-Mar-10 7:09 
GeneralNice Pinmembersamerh28-Jan-10 23:55 
GeneralRe: Nice Pinmemberrperetz1-Feb-10 16:25 
GeneralMy vote of 1 PinmvpDave Kreskowiak28-Jan-10 12:44 
GeneralRe: My vote of 1 Pinmemberrperetz1-Feb-10 16:14 

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