Overview:

Binding to List Controls, finding the selected values, and checking and unchecking the items are some of the joys of asp.net development... And while I'd hate to deprive anyone of those simple pleasures, for those souls who find it a tedious chore I offer the List Control Utility. This library will streamline the following tasks:

1. Binding values to a List Control.
2. "Checking" or "Selecting" a set of items in a List Control.
3. Applying styles to an individual List Item.
4. Retrieving all "Checked" or "Selected" items to CSV or XML.
5. Putting on your pants --just seeing if your paying attention.

Methods

below is a list of the method names and descriptions in the List Control Utility. I did not give the signatures, but many of these have several overloads. You can view all the methods, their overloads, and documentation by clicking on the "View the Code" button below or by just downloading the .cs file.

• DoListControl: Simplifies binding to a List Control. Can aslo be used to "pre-select" values in the List Control.
• ApplyListItemStyles: Apply a CSS Style to the passed List Items values.
• SelectByValue: Selects all List Items whose value matches the passed values.
• SelectByText: Selects all List Items whose text matches the passed text.
• SelectedItemsValueToCSV: Returns a comma seperated list of all the selected List Item values.
• SelectedItemsTextToCSV: Returns a comma seperated list of all the selected List Item text.
• SelectedItemsToXML: Returns a string XML fragment that contains the selected List Items value and text.
• ClearAllSelectedItems: Unselects all selected List Items.

C# String Library: 
using System;
using System.Collections;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Text;
using System.Xml;
using System.Web.UI ;
using System.Web.UI.WebControls;

namespace CoreWebLibrary.Web.ControlUtilities
{
   public static class ListControlHelper
   {
      public static void DoListControl(ListControl lc,
           IList items)
      {
         DoListControl(lc, items, string.Empty, string.Empty, false);
      }

      public static void DoListControl(ListControl lc,
           IList items, string textfield, string valuefield)
      {
         DoListControl(lc, items, textfield, valuefield, false);
      }

      public static void DoListControl(ListControl lc,
           IList items, string textfield, string valuefield,
           bool throwErrorOnNotFound, params string[] valuesToSelect)
      {
         DoListControl(lc, items, textfield, valuefield, FindListItemBy.ByValue, throwErrorOnNotFound);
      }

      public static void DoListControl(ListControl lc,
          IList items, string textfield, string valuefield,
          FindListItemBy selectedType, bool throwErrorOnNotFound,
          params string[] valuesToSelect)
      {
         lc.DataSource = items;
         lc.DataTextField = textfield;
         lc.DataValueField = valuefield;
         lc.DataBind();

         if (valuesToSelect.Length > 0)
            ListControlHelper.Select(lc, throwErrorOnNotFound,
            selectedType, valuesToSelect);
      }

      public static void DoListControl(ListControl lc,
           IListSource items, string textfield, string valuefield)
      {
         DoListControl(lc, items, textfield, valuefield, false);
      }

      public static void DoListControl(ListControl lc,
           IListSource items, string textfield, string valuefield,
           bool throwErrorOnNotFound, params string[] valuesToSelect)
      {
         DoListControl(lc, items, textfield, valuefield, FindListItemBy.ByValue, throwErrorOnNotFound);
      }

      public static void DoListControl(ListControl lc,
          IListSource items, string textfield, string valuefield,
          FindListItemBy selectedType, bool throwErrorOnNotFound,
          params string[] valuesToSelect)
      {
         lc.DataSource = items;
         lc.DataTextField = textfield;
         lc.DataValueField = valuefield;
         lc.DataBind();

         if (valuesToSelect.Length > 0)
            ListControlHelper.Select(lc, throwErrorOnNotFound,
            selectedType, valuesToSelect);
      }

      public static void DoListControl(ListControl lc,
          IDictionary items)
      {
         DoListControl(lc, items, "Value", "Key", FindListItemBy.ByValue,
            false);
      }

      public static void DoListControl(ListControl lc,
          IDictionary items, string textfield, string valuefield)
      {
         DoListControl(lc, items, textfield, valuefield, FindListItemBy.ByValue,
            false);
      }

      public static void DoListControl(ListControl lc,
          IDictionary items, string textfield, string valuefield,
          bool throwErrorOnNotFound,
          params string[] valuesToSelect)
      {
         DoListControl(lc, items, textfield, valuefield, FindListItemBy.ByValue,
            throwErrorOnNotFound, valuesToSelect);
      }

      public static void DoListControl(ListControl lc,
          IDictionary items, string textfield, string valuefield,
          FindListItemBy selectedType, bool throwErrorOnNotFound,
          params string[] valuesToSelect)
      {
         lc.DataSource = items;
         lc.DataTextField = textfield;
         lc.DataValueField = valuefield;
         lc.DataBind();

         if (valuesToSelect.Length > 0)
            ListControlHelper.Select(lc, throwErrorOnNotFound,
            selectedType, valuesToSelect);
      }
        
      public static void ApplyListItemStyles(ListControl lc,
         IDictionary styles,
         params string[] valuesToApplyTo)
      {
         foreach (string s in valuesToApplyTo)
         {
            ListItem item = lc.Items.FindByValue(s);
            if (item != null)
            {
               CssStyleCollection css = item.Attributes.CssStyle ;

               foreach (KeyValuePair style in styles)
               {
                  css.Add(style.Key, style.Value);
               }
            }
         }
      }

      public static void ApplyListItemStyles(ListControl lc,
         IDictionary styles,
         params ListItem[] itemsToApplyTo)
      {
         foreach (ListItem item in itemsToApplyTo)
         {
            CssStyleCollection css = item.Attributes.CssStyle;

            foreach (KeyValuePair style in styles)
            {
               css.Add(style.Key, style.Value);
            }
         }
      }

      public static void SelectByValue(ListControl lc,
         params string[] valuesToSelect)
      {
         ListControlHelper.Select(lc, false,
            FindListItemBy.ByValue, valuesToSelect);
      }

      public static void SelectByValue(ListControl lc, 
         bool throwErrorOnNotFound, 
         params string[] valuesToSelect)
      {
         ListControlHelper.Select(lc, throwErrorOnNotFound,
            FindListItemBy.ByValue, valuesToSelect);
      }

      public static void SelectByText(ListControl lc,
         params string[] valuesToSelect)
      {
         ListControlHelper.Select(lc, false,
            FindListItemBy.ByText, valuesToSelect);
      }

      public static void SelectByText(ListControl lc,
         bool throwErrorOnNotFound,
         params string[] valuesToSelect)
      {
         ListControlHelper.Select(lc, throwErrorOnNotFound,
            FindListItemBy.ByText, valuesToSelect);
      }

      public static string SelectedItemsValueToCSV(ListControl lc)
      {
         StringBuilder sb = new StringBuilder();
         foreach (ListItem item in lc.Items)
         {
            if (item.Selected)
               sb.AppendFormat("{0},", item.Value);
         }

         return sb.ToString().TrimEnd(',');
      }

      public static string SelectedItemsTextToCSV(ListControl lc)
      {
         StringBuilder sb = new StringBuilder();
         foreach (ListItem item in lc.Items)
         {
            if (item.Selected)
               sb.AppendFormat("{0},", item.Text);
         }

         return sb.ToString().TrimEnd(',');
      }

      public static string SelectedItemsToXML(ListControl lc, string nodeName)
      {
         StringBuilder sb = new StringBuilder();
         sb.AppendFormat("<{0}>", nodeName);
         
         foreach (ListItem item in lc.Items)
         {
            if (item.Selected)
            {
               sb.AppendFormat("",
               item.Text, item.Value);
            }
         }
         
         sb.AppendFormat("", nodeName);

         return sb.ToString();
      }

      public static void ClearAllSelectedItems(ListControl lc)
      {
         if (lc is DropDownList)
         {
            if (lc.SelectedItem != null)
               lc.SelectedItem.Selected = false;         
         }
         else
         {
            foreach (ListItem item in lc.Items)
            {
               item.Selected = false;
            }         
         }
      }
    
      #region Private Methods

      private static void Select(ListControl lc,
         bool throwErrorOnNotFound,
         FindListItemBy findBy,
         params string[] valuesToSelect)
      {
         foreach (string s in valuesToSelect)
         {
            ListItem item = ItemFindBy(lc, s, findBy);
            if (item != null)
            {
               item.Selected = true;
            }
            else if (throwErrorOnNotFound)
            {
               throw new ApplicationException(string.Format("Value: {0} not found in ListControl {1}",
                  s, lc.ID));
            }
         }
      }

      private static ListItem ItemFindBy(ListControl lc, 
         string value, 
         FindListItemBy findBy)
      {
         if (findBy == FindListItemBy.ByText)
            return lc.Items.FindByText(value);
         
         if (findBy == FindListItemBy.ByValue)
            return lc.Items.FindByValue(value);

         return null;
      }

      #endregion

      #region Public Enum

      public enum FindListItemBy
      {
         ByValue,
         ByText
      }

      #endregion
   }
}

Use & Examples

below are a few examples of how to use the List Control Utility. It is a fairly straight forward collection of ListControl utilities so a few minutes of experimentation ought to suffice to learn how to use it.

public void SomeMethod()
{
    //assumes there is a CheckBoxList on the aspx names cblNames
    Dictionary<string, string> items = new Dictionary<string, string>();
    items.Add("123", "Jack");
    items.Add("456", "Jill");
    items.Add("789", "Steve");

    ListControlHelper.DoListControl(cblNames, items, "Value", "Key", false, "123");
}

public void SomeMethod()
{
   //assumes there is a CheckBoxList on the aspx names cblDays like the one below.
   ListControlHelper.SelectByValue(cblDays, "Mon", "Wed", "Fri");
}

public void SomeMethod()
{
   //To convert the selected item in the "cblDays" CheckBoxList to
   //XML and CSV you would use:
   string xml = ListControlHelper.SelectedItemsToXML(cblDays, "Days");
   string csv = ListControlHelper.SelectedItemsValueToCSV(cblDays);
}

<Days>
   <item text="Monday" value="Mon" selected="true" />
   <item text="Wednesday" value="Wed" selected="true" />
   <item text="Friday" value="Fri" selected="true" />
</Days>

public void SomeMethod()
{
   //assumes there is a CheckBoxList on the aspx names cblDaysTwo like the one below.
    Dictionary<HtmlTextWriterStyle, string> styles = 
      new Dictionary<HtmlTextWriterStyle,string>();
    styles.Add(HtmlTextWriterStyle.FontWeight, "bold");
    styles.Add(HtmlTextWriterStyle.Color, "Green");
    ListControlHelper.ApplyListItemStyles(cblDaysTwo, styles, "Mon", "Wed", "Fri");
}

Conclusion

happy binding! If you extend the library, please send me what you've done.