Bind ListBox, Retrieve The Multi-selected Values And Pre-select ListBox in ASP.NET WebForm

I will cover following topics for ListBox:

How to bind List Box with Database?
How to retrieve the Multi Selected value?
How to Pre-select List Box Items from Database?

List box control allows user to select single or multiple item selection. Partially it's similar to a dropdown list.

The following are the main properties of ListBox control.

Rows: By Default there is 4 rows setting , you can change according to your requirement.
SelectionMode: By default SINGLE is selected, you can change to MULTIPLE.
DataTextField: Field Name which display on list box.
DataValueField: Field Name which ID value you going to store in saving table.
Items: Hard coded value store in List Box.

Table Structure:

USE [MemberCDAC]
GO
/****** Object: Table [dbo].[tblTechnologies] Script Date: 02/07/2016 18:03:35 ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
SET ANSI_PADDING ON
GO
CREATE TABLE [dbo].[tblTechnologies](
[TechID] [int] IDENTITY(1,1) NOT NULL,
[TechName] [varchar](50) NULL
) ON [PRIMARY]
GO
SET ANSI_PADDING OFF

Create a ASP.NET web site project.

Give Project name : ListBoxSample.

Now right click on Solution Explorer and Add new web page/form.

Right Click->ADD->ADD NEW ITEM

Add new item in project

Add the WebForm, named : SimpleListBoxBind.aspx.

In SimpleListBoxBind.aspx , we are going to bind List box from database with multi selections options.

Now double clicked on SimpleListBoxBind.aspx file.

Drag n Drop the List Box control on aspx page.

While you click smart tag menu option.

Smart Tag Menu Options:

Choose Data Source: Non-programmatically and with Wizard we can populate List Box items.
Edit Items: Hard coded items for List Box.
Enable AutoPostBack: Mark and ready List box for auto post back to server while we select any item(s).

How To Bind List Box From Database?

CODE of SimpleListBoxBind.aspx file

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="SimpleListBoxBind.aspx.cs" Inherits="SimpleListBoxBind" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ListBox ID="lstTech" runat="server" Height="240px" SelectionMode="Multiple" Width="190px" BackColor="#CCFFFF"></asp:ListBox>
</div>
</form>
</body>
</html>

CODE of SimpleListBoxBind.aspx.cs file

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class SimpleListBoxBind: System.Web.UI.Page
{
string ConStr = ConfigurationManager.ConnectionStrings["MemberCDACConnectionString"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindListBox();
}
}
/// <summary>
/// To load data into ListBox control
/// </summary>
public void BindListBox()
{
SqlConnection con = new SqlConnection(ConStr);
SqlDataAdapter da = new SqlDataAdapter("Select * From tblTechnologies", ConStr);
DataSet ds = new DataSet();
da.Fill(ds, "TechTable");
lstTech.DataSource = ds;
lstTech.DataTextField = "TechName";
lstTech.DataValueField = "TechID";
lstTech.DataBind();
}
}

Output:

see output

In above image you can see, I had selected the following Items:

ASP.NET MVC
C#
JavaScript
MS SQL Server

How to retrieve the Multi Selected value?

Now, we are going forward for How to Retrieve the Multi Selected Value from List Box.

Now right click on Solution Explorer and Add new web page/form.

RightClick->ADD->ADD NEW ITEM

select web page

Give file name: ListBoxSelecetedItem.aspx.

Now double clicked on SimpleListBoxBind.aspx file.

Drag n Drop the List Box control on aspx page.

In this page following controls selected:

Control	Control ID	Description
List Box	lstTech	Contains all the items for selections.
Button	btnSubmit	Button to Submit the Selected Items.
Label	lblSelectedTech	Label to display selected Technologies items.

CODE of ListBoxSelectedItem.aspx file

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ListBoxSelectedItem.aspx.cs" Inherits="ListBoxSelectedItem" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ListBox ID="lstTech" runat="server" Height="240px" SelectionMode="Multiple" Width="190px" BackColor="#CCFFFF"></asp:ListBox> <br /> <br />
<asp:Button ID="btnSubmit" runat="server" OnClick="btnSubmit_Click" Text="Submit" /> <br /> <br /> <br />
<asp:Label ID="lblSelectedTech" runat="server" Text="[Selected Technologies]"></asp:Label> <br />
</div>
</form>
</body>
</html>

CODE of ListBoxSelectedItem.aspx.cs file

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class ListBoxSelectedItem: System.Web.UI.Page
{
string ConStr = ConfigurationManager.ConnectionStrings["MemberCDACConnectionString"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindListBox();
}
}
/// <summary>
/// To load data into ListBox control
/// </summary>
public void BindListBox()
{
SqlConnection con = new SqlConnection(ConStr);
SqlDataAdapter da = new SqlDataAdapter("Select * From tblTechnologies", ConStr);
DataSet ds = new DataSet();
da.Fill(ds, "TechTable");
lstTech.DataSource = ds;
lstTech.DataTextField = "TechName";
lstTech.DataValueField = "TechID";
lstTech.DataBind();
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
lblSelectedTech.Text = "You have Seleceted Following Technologies: ";
foreach(ListItem item in lstTech.Items)
{
if (item.Selected)
{
lblSelectedTech.Text += "<li><b>" + item.Text + "<b></li>";
}
}
}
}

Output:

run

How to Pre-select List Box Items from Database?

Now, we are going forward for Pre-Select List Box Items programmatically.

Now right click on Solution Explorer and Add new web page/form.

RightClick->ADD->ADD NEW ITEM.

Give file name: ListBoxSelecetedItem.aspx.

Now double clicked on SimpleListBoxBind.aspx file.

Drag n Drop the List Box control on aspx page.

In this page following controls selected:

Control	Control ID	Description
List Box	lstTech	Contains all the items for selections.
Button	btnSubmit	Button to Submit the Selected Items.
Label	lblSelectedTech	Label to display selected Technologies items.

Following are our Pre selected values:

ASP.NET Web Form
C#
JavaScript
VB.NET

CODE of PreSelectListBoxItems.aspx file

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ListBoxSelectedItem.aspx.cs" Inherits="ListBoxSelectedItem" %>
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head id="Head1" runat="server">
<title></title>
</head>
<body>
<form id="form1" runat="server">
<div>
<asp:ListBox ID="lstTech" runat="server" Height="240px" SelectionMode="Multiple" Width="190px" BackColor="#CCFFFF"></asp:ListBox> <br /> <br />
<asp:Button ID="btnSubmit" runat="server" OnClick="btnSubmit_Click" Text="Submit" /> <br /> <br /> <br />
<asp:Label ID="lblSelectedTech" runat="server" Text="[Selected Technologies]"></asp:Label> <br />
</div>
</form>
</body>
</html>

CODE of PreSelectListBoxItems.aspx.cs file

using System;
using System.Collections.Generic;
using System.Configuration;
using System.Data;
using System.Data.SqlClient;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
public partial class PreSelectListBoxItems: System.Web.UI.Page
{
string ConStr = ConfigurationManager.ConnectionStrings["MemberCDACConnectionString"].ConnectionString;
protected void Page_Load(object sender, EventArgs e)
{
if (!IsPostBack)
{
BindListBox();
PreSelectItem();
}
}
/// <summary>
/// To load data into ListBox control
/// </summary>
public void BindListBox()
{
SqlConnection con = new SqlConnection(ConStr);
SqlDataAdapter da = new SqlDataAdapter("Select * From tblTechnologies", ConStr);
DataSet ds = new DataSet();
da.Fill(ds, "TechTable");
lstTech.DataSource = ds;
lstTech.DataTextField = "TechName";
lstTech.DataValueField = "TechID";
lstTech.DataBind();
}
protected void btnSubmit_Click(object sender, EventArgs e)
{
DisplaySelectedItems();
}
public void PreSelectItem()
{
//Selected Items which selected programmatically.
List < string > _selectedTechnology = new List < string > ();
_selectedTechnology.Add("ASP.NET Web Form");
_selectedTechnology.Add("C#");
_selectedTechnology.Add("JavaScript");
_selectedTechnology.Add("VB.NET");
if ((lstTech.Items.Count > 0) && (_selectedTechnology.Count > 0))
{
for (int i2 = 0; i2 < lstTech.Items.Count; i2++)
{
for (int i = 0; i < _selectedTechnology.Count; i++)
{
if (lstTech.Items[i2].Text.ToString().Trim() == _selectedTechnology[i].ToString().Trim())
{
lstTech.Items[i2].Selected = true;
}
}
}
}
DisplaySelectedItems();
}
public void DisplaySelectedItems()
{
lblSelectedTech.Text = "You have Seleceted Following Technologies: ";
foreach(ListItem item in lstTech.Items)
{
if (item.Selected)
{
lblSelectedTech.Text += "<li><b>" + item.Text + "<b></li>";
}
}
}
}

Output:

Output