Custom .NET Validator for CheckBoxList control

Here is a User Control that serves as a custom validator for a .NET CheckBoxList control.

ASCX file:

1. <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="CheckBoxListCustomValidator.ascx.cs" Inherits="MARE.Directory.UserControls.CheckBoxListCustomValidator" ClientIDMode="AutoID" %>
2. <asp:CustomValidator ID="valCheckBoxList" class="error" EnableClientScript="true" Text="Required" ErrorMessage="Required" runat="server" />
3.  
4. <script type="text/javascript">
5.     (function ($) {
6.  
7.         <%= ClientValidationMethodName %> = function (sender, e) {
8.             var $checkBoxList = $('#<%= CheckBoxListToValidate.ClientID %>');
9.             e.IsValid = $checkBoxList.find(':checkbox:checked').length > 0;
10.         };
11.  
12.         $(document).ready(function () {
13.             var $checkBoxList = $('#<%= CheckBoxListToValidate.ClientID %>');
14.             // setup validation
15.             $checkBoxList.find(':checkbox').click(function () {
16.                 // .NET validate the checkbox list
17.                 var validator = document.getElementById('<%= valCheckBoxList.ClientID %>');
18.                 ValidatorValidate(validator);
19.             });
20.         });
21.  
22.     })(jQuery);
23. </script>

Code-behind:

1. using System;
2. using System.Web.UI;
3. using System.Web.UI.WebControls;
4.  
5. namespace MARE.Directory.UserControls
6. {
7.     public partial class CheckBoxListCustomValidator : System.Web.UI.UserControl
8.     {
9.         private CheckBoxList _checkBoxListToValidate;
10.  
11.         protected void Page_Load(object sender, EventArgs e)
12.         {
13.             if (!string.IsNullOrEmpty(ControlToValidate))
14.             {
15.                 _checkBoxListToValidate = FindCheckBoxListRecursive(this.Page, ControlToValidate);
16.             }
17.             valCheckBoxList.ClientValidationFunction = ClientValidationMethodName;
18.             valCheckBoxList.ServerValidate += ValidateCheckBoxList;
19.         }
20.  
21.         private string _clientValidationMethodName;
22.         public string ClientValidationMethodName
23.         {
24.             get
25.             {
26.                 if (_clientValidationMethodName == null)
27.                 {
28.                     _clientValidationMethodName = string.Format("window.val{0}", Guid.NewGuid().ToString("N"));
29.                 }
30.                 return _clientValidationMethodName;
31.             }
32.         }
33.  
34.         public string ControlToValidate { get; set; }
35.  
36.         public CheckBoxList CheckBoxListToValidate { get { return _checkBoxListToValidate; } }
37.  
38.         public CustomValidator CheckBoxListValidator { get { return valCheckBoxList; } }
39.  
40.         public string ValidatorText
41.         {
42.             get { return CheckBoxListValidator.Text; }
43.             set { CheckBoxListValidator.Text = value; }
44.         }
45.  
46.         public string ValidatorErrorMessage
47.         {
48.             get { return CheckBoxListValidator.ErrorMessage; }
49.             set { CheckBoxListValidator.ErrorMessage = value; }
50.         }
51.  
52.         public void SetCheckBoxListToValidate(CheckBoxList checkBoxListToValidate)
53.         {
54.             _checkBoxListToValidate = checkBoxListToValidate;
55.         }
56.  
57.         internal void ValidateCheckBoxList(object sender, ServerValidateEventArgs e)
58.         {
59.             bool isValid = false;
60.             int i = 0;
61.  
62.             while (i < _checkBoxListToValidate.Items.Count && !isValid)
63.             {
64.                 ListItem li = _checkBoxListToValidate.Items[i];
65.                 isValid = li.Selected;
66.                 i++;
67.             }
68.  
69.             e.IsValid = isValid;
70.         }
71.  
72.         private static CheckBoxList FindCheckBoxListRecursive(Control control, string id)
73.         {
74.             if (control == null) return null;
75.             //try to find the control at the current level
76.             CheckBoxList ctrl = control.FindControl(id) as CheckBoxList;
77.  
78.             if (ctrl == null)
79.             {
80.                 //search the children
81.                 foreach (Control child in control.Controls)
82.                 {
83.                     ctrl = FindCheckBoxListRecursive(child, id);
84.  
85.                     if (ctrl != null) break;
86.                 }
87.             }
88.             return ctrl;
89.         }
90.     }
91. }

Implementation:

1. <%@ Control Language="C#" AutoEventWireup="true" CodeBehind="MyUserControl.ascx.cs" Inherits="MARE.Directory.UserControls.MyUserControl" %>
2. <%@ Register Src="../UserControls/CheckBoxListCustomValidator.ascx" TagPrefix="uc1" TagName="CheckBoxListCustomValidator" %>
3.  
4. <asp:CheckBoxList ID="cblMyCheckboxList1" RepeatDirection="Horizontal" RepeatColumns="4" runat='server' />        
5. <uc1:CheckBoxListCustomValidator runat="server" id="valcblMyCheckboxList1" ControlToValidate="cblMyCheckboxList1" ValidatorErrorMessage="Required" />
6.  
7. <asp:CheckBoxList ID="cblMyCheckboxList2" RepeatDirection="Horizontal" RepeatColumns="4" runat='server' />        
8. <uc1:CheckBoxListCustomValidator runat="server" id="valcblMyCheckboxList2" ControlToValidate="cblMyCheckboxList2" ValidatorErrorMessage="Required" />