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CheckedListBox User Control - ASP.NET

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Modified on Wed, Oct 20, 2010, 12:30 PM by Administrator Categorized as ASP·NET Web Forms
This page is part of the Class Library Pages collection.
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Table of Contents [Hide/Show]


   Consuming the Control
      ASPX Markup Code
      ASPX Markup Code for Validation Control
      JavaScript Code for Validation
      Code-Behind
         VB.NET (in a GridView)
         C#
   Code for the Control
         ASPX Markup for VB.NET
         ASPX Markup for C#
         VB.NET
         C#

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Consuming the Control

ASPX Markup Code

To use this control, you need to follow the instructions in the Consuming Custom Controls in ASP.NET article.

Placing the control

<abc:CheckedListBox Columns="3" ID="uxRegionsListBox" 
    runat="server" EnableViewState="true" 
    />

ASPX Markup Code for Validation Control

<asp:CustomValidator runat="server" Text="" Display="Dynamic"
    SetFocusOnError="true" ValidationGroup="MainValidationGroup"
    EnableClientScript="true"
    ClientValidationFunction="validateRegions"
    OnServerValidate="uxRegionsRequiredValidator_Validate"
    ID="uxRegionsRequiredValidator"
    ErrorMessage="At least one region must be selected."
    >
    
    <asp:Image ID="Image5" runat="server" 
        ImageUrl="~/images/Exclamation.PNG" />
    
    </asp:CustomValidator>

JavaScript Code for Validation

Be sure to change "uxRegionsListBox" to the name of your checkbox control.

// This is a helper function
function validateCheckedListBox(e, id)
{
    var selectedCheckBoxes;
    selectedCheckBoxes = 0;
    
    for (i = 0; i < document.forms[0].elements.length; i++)
    { 
        var ctl;
        ctl = document.forms[0].elements[i];
        
        if (ctl.type == "checkbox" & ctl.id.indexOf(id) >= 0) 
        {
            if (ctl.checked)
                selectedCheckBoxes++;
        }
    }
    
    e.IsValid = (selectedCheckBoxes > 0);
}
// This is the function called on the client side to validate the checked-list-box.
function validateRegions(sender, e)
{
    validateCheckedListBox(e, "uxRegionsListBox");
}

Code-Behind

VB.NET (in a GridView)

'--------------------------------------------------------------------------------------------------
Private Sub uxSearchResultsGridView_RowDataBound(ByVal sender As Object, ByVal e As _
GridViewRowEventArgs) Handles uxSearchResultsGridView.RowDataBound

    If e.Row.RowType = DataControlRowType.DataRow Then

        UserControl_CheckedListBox.BindCheckedListBox(e.Row, "uxRegionsListBox", GetRegions(), _
                    "Name", "RegionId", "Regions")

    End If

End Sub
'--------------------------------------------------------------------------------------------------
Protected Sub uxRegionsRequiredValidator_Validate(ByVal sender As Object, ByVal e As _
ServerValidateEventArgs)

    e.IsValid = (uxRegionsListBox.ItemsChecked > 0)

End Sub

C#

//TODO: Add C# code here

Code for the Control

ASPX Markup for VB.NET

<%@ Control Language="VB" AutoEventWireup="false" CodeFile="CheckedListBox.ascx.vb" 
Inherits="UserControls_CheckedListBox" EnableViewState="true" %>

<div style="overflow:auto;" runat="server" id="uxMainDiv" />

ASPX Markup for C#

<%@ Control Language="C#" AutoEventWireup="false" CodeFile="CheckedListBox.ascx.cs" 
Inherits="UserControls_CheckedListBox" EnableViewState="true" %>

<div style="overflow:auto;" runat="server" id="uxMainDiv" />

VB.NET

Imports System.Data
Imports System.Collections.Generic

<ValidationProperty("ItemsChecked")> _
Partial Class UserControls_CheckedListBox
    Inherits System.Web.UI.UserControl

    Private _dataSource As DataTable
    Private _dataTextField As String
    Private _dataValueField As String
    Private _items As Dictionary(Of String, CheckBox)
    Private _itemValues As Dictionary(Of String, Integer)
    Private _columns As Integer

    '----------------------------------------------------------------------------------------------
    Public Sub New()

        _items = New Dictionary(Of String, CheckBox)
        _itemValues = New Dictionary(Of String, Integer)
        _columns = 1

    End Sub
    '----------------------------------------------------------------------------------------------
    Public Property Columns() As Integer
        Get
            Return _columns
        End Get
        Set(ByVal value As Integer)
            _columns = value
        End Set
    End Property
    '----------------------------------------------------------------------------------------------
    Public Property DataSource() As DataTable
        Get
            Return _dataSource
        End Get
        Set(ByVal value As DataTable)
            _dataSource = value
        End Set
    End Property
    '----------------------------------------------------------------------------------------------
    Public Property DataTextField() As String
        Get
            Return _dataTextField
        End Get
        Set(ByVal value As String)
            _dataTextField = value
        End Set
    End Property
    '----------------------------------------------------------------------------------------------
    Public Property DataValueField() As String
        Get
            Return _dataValueField
        End Get
        Set(ByVal value As String)
            _dataValueField = value
        End Set
    End Property
    '----------------------------------------------------------------------------------------------
    Public Overrides Sub DataBind()

        Dim i As Integer = 0

        Dim tbl As Table = New Table()
        tbl.CellPadding = 3
        tbl.CellSpacing = 0
        tbl.BorderStyle = BorderStyle.None

        Dim tr As TableRow = Nothing

        If _dataSource IsNot Nothing Then

            For Each row As DataRow In _dataSource.Rows

                Dim text As String = row(_dataTextField)
                Dim value As Integer = Convert.ToInt32(row(_dataValueField))

                Dim cb As CheckBox = New CheckBox
                cb.Text = text
                cb.Checked = False
                cb.CssClass = "stdData"

                _items.Add(text, cb)
                _itemValues.Add(text, value)

                Dim td As TableCell = New TableCell()
                td.Controls.Add(cb)

                If i Mod _columns = 0 Then
                    tr = New TableRow()
                    tbl.Rows.Add(tr)
                End If

                tr.Cells.Add(td)

                i += 1

            Next

        End If

        uxMainDiv.Controls.Add(tbl)

    End Sub
    '----------------------------------------------------------------------------------------------
    Public ReadOnly Property Items() As Dictionary(Of String, CheckBox)
        Get
            Return _items
        End Get
    End Property
    '----------------------------------------------------------------------------------------------
    Public ReadOnly Property ItemValues() As Dictionary(Of String, Integer)
        Get
            Return _itemValues
        End Get
    End Property
    '----------------------------------------------------------------------------------------------
    ''' <summary>
    ''' This property is used only for validation purposes.
    ''' </summary>
    Public ReadOnly Property ItemsChecked() As Integer
        Get
            Dim result As Integer = 0
            For Each key As String In _itemValues.Keys
                If _items(key).Checked Then
                    result += 1
                    Exit For
                End If
            Next
            Return result
        End Get
    End Property
    '----------------------------------------------------------------------------------------------
    ''' <summary>
    ''' This method should be called UNCONDITIONALLY in the Page_Load event.  See also the Bind() 
    '''     method.
    ''' </summary>
    Public Sub InitCheckBoxes(ByVal itemSource As DataTable, ByVal dataTextField As String, ByVal _
    dataValueField As String)

        Me.DataSource = itemSource
        Me.DataTextField = dataTextField
        Me.DataValueField = dataValueField
        Me.DataBind()

    End Sub
    '----------------------------------------------------------------------------------------------
    ''' <summary>
    ''' This method should be called only if: Not Page.IsPostBack!  See also the Init() method
    ''' </summary>
    Public Sub Bind(ByVal checkedValues As String, ByVal delimiter As String)

        Dim items() As String = checkedValues.ToString().Split(delimiter)
        For Each item As String In items
            Me.Items(item).Checked = True
        Next

    End Sub
    '----------------------------------------------------------------------------------------------
    ''' <summary>
    ''' Use this method to create a checked listbox within a GridView control when the row
    ''' goes into edit mode.  MUST BE CALLED FROM THE ROWDATABOUND EVENT HANDLER.
    ''' </summary>
    Public Shared Sub BindCheckedListBox(ByVal gvRow As GridViewRow, ByVal checkedListBox As String, _
    ByVal itemSource As DataTable, ByVal dataTextField As String, ByVal dataValueField As String, _
    ByVal fieldName As String)

        Dim clb As UserControl_CheckedListBox = gvRow.FindControl(checkedListBox)

        If clb IsNot Nothing Then

            clb.DataSource = itemSource
            clb.DataTextField = dataTextField
            clb.DataValueField = dataValueField
            clb.DataBind()

            Dim row As DataRow = Nothing

            Dim drv As DataRowView = CType(gvRow.DataItem, DataRowView)

            If drv IsNot Nothing Then
                row = drv.Row
            End If


            If row IsNot Nothing Then
                Dim regions() As String = row(fieldName).ToString().Split("^"c)
                For Each region As String In regions
                    clb.Items(region).Checked = True
                Next
            End If

        End If

    End Sub

End Class

C#

//TODO: Add the C# code

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