[Mono-list] ASP.NET CheckBoxList Control

[John Anderson]

Hey, I'm trying to implement my own CheckBoxList control based off of
mono's.  But for some reason my LoadPostData method doesn't get fired, can
anyone see anything wrong?

using System.Collections.Generic;
using System.Collections.Specialized;
using System.ComponentModel;
using System.Security.Permissions;
using System.Web.UI.WebControls;
using System.Web.UI;
using System;
using System.Text;
using System.IO;
namespace Orchid.Web.Controls
{
    /// <summary> A checkboxlist control that uses ajax callbacks for
sorting</summary>
    public class SortableCheckBoxList : ListControl, INamingContainer,
IPostBackDataHandler
    {
        private CheckBox checkBox;
        public SortableCheckBoxList()
        {
            checkBox = new CheckBox();
            Controls.Add(checkBox);
        }
        protected override void OnPreRender(EventArgs e)
        {
            base.OnPreRender(e);
            for (int count = 0; count < Items.Count; count++)
            {
                if (Items[count].Selected)
                {
                    checkBox.ID = String.Format("chk_item_{0}",
count.ToString());
                    Page.RegisterRequiresPostBack(checkBox);
                }
            }
        }
        protected override void OnLoad(EventArgs e)
        {
            base.OnLoad(e);
            string sortId = String.Format("{0}[]", ID);
            if (Page.Request.Form[sortId] != null && !Page.IsPostBack)
            {
                string[] sortedItems = Page.Request.Form[sortId].Split(',');
                SortedItems = new int[sortedItems.Length];
                for (int count = 0; count < sortedItems.Length; count++)
                    SortedItems[count] = int.Parse(sortedItems[count]);
            }
        }
        public int[] SortedItems
        {
            get { return (int[])Page.Session[this.ID + "SortedItems"]; }
            set { Page.Session[this.ID + "SortedItems"] = value; }
        }
        protected override void Render(HtmlTextWriter writer)
        {
            if (Items == null || Items.Count == 0)
                return;
            writer.AddAttribute(HtmlTextWriterAttribute.Id, ID);
            writer.AddAttribute(HtmlTextWriterAttribute.Class, CssClass);
            writer.RenderBeginTag(HtmlTextWriterTag.Ul);

            if (SortedItems == null)
            {
                for (int itemIndex = 0; itemIndex < Items.Count;
itemIndex++)
                {
                    RenderListItem(itemIndex, writer);
                }
            }
            else
            {
                foreach (int itemIndex in SortedItems)
                {
                    RenderListItem(itemIndex, writer);
                }
            }
            writer.RenderEndTag();
            StringBuilder sb = new StringBuilder();

            string ajaxCallBack = String.Format("function() {{ new
Ajax.Request('{0}?ajaxAction={2}{3}',{{asynchronous:true, parameters:
Sortable.serialize('{1}')}})}}",
                                                 Path.GetFileName(
Page.Request.PhysicalPath), ID, new Random().Next(), GetQueryString());
            sb.AppendLine(String.Format("Sortable.create('{0}',
{{onUpdate:{1}, asynchronous:true, dropOnEmpty:true,constraint:
false,overlap:'horizonal'}});",
                                        ID, ajaxCallBack));
            Page.ClientScript.RegisterStartupScript(this.Page.GetType(),
"draggable", sb.ToString(), true);
        }
        private string GetQueryString()
        {
            int count = Page.Request.QueryString.Count;
            if (count > 0)
            {
                StringBuilder queryString = new StringBuilder();
                for (int index = 0; index < count; index++)
                {
                    queryString.AppendFormat("&{0}={1}",
Page.Request.QueryString.Keys[index], Page.Request.QueryString[index]);
                }
                return queryString.ToString();
            }
            return string.Empty;
        }
        private void RenderListItem(int index, HtmlTextWriter writer)
        {
            ListItem item = Items[index];
            writer.AddAttribute(HtmlTextWriterAttribute.Id,
String.Format("item_{0}",
index));
            writer.RenderBeginTag(HtmlTextWriterTag.Li);
            checkBox.ID = String.Format("chk_item_{0}", index.ToString());
            checkBox.Text = item.Text;
            checkBox.AutoPostBack = AutoPostBack;
            checkBox.Enabled = Enabled;
            checkBox.ValidationGroup = ValidationGroup;
            checkBox.CausesValidation = CausesValidation;
            checkBox.Checked = item.Selected;
            checkBox.RenderControl(writer);
            writer.RenderEndTag();
        }

        #region IPostBackDataHandler Members

        public bool LoadPostData(string postDataKey, NameValueCollection
postCollection)
        {
            EnsureDataBound();
            int checkboxIndex = -1;

            try
            {
                string id = postDataKey.Substring(ClientID.Length + 1);
                if (Char.IsDigit(id[0]))
                    checkboxIndex = Int32.Parse(id);
            }
            catch
            {
                return false;
            }
            if (checkboxIndex == -1)
                return false;

            string val = postCollection[postDataKey];
            bool isChecked = val == "on";
            ListItem item = Items[checkboxIndex];
            if (item.Selected != isChecked)
            {
                item.Selected = isChecked;
                return true;
            }
            return false;
        }

        public void RaisePostDataChangedEvent()
        {
            if (CausesValidation)
                Page.Validate(ValidationGroup);
            OnSelectedIndexChanged(EventArgs.Empty);

        }

        #endregion
    }
}
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