CascadingListDecorator for WinForms

CascadingListDecorator.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Windows.Forms;

namespace Samples
{
    public class CascadingListDecorator<TChildValue, TParentValue> where TParentValue : class
    {
        private ListControl _childList;
        private Func<TParentValue, IList<TChildValue>> _DynamicDataSource;
        private ListControl _parentList;

        public CascadingListDecorator(ListControl child)
        {
            _childList = child;
            _childList.Enabled = false;
            AutoSelectSoloItem = false;
        }

        public Func<TParentValue, IList<TChildValue>> DynamicDataSource
        {
            get { return _DynamicDataSource; }
            set
            {
                _DynamicDataSource = value;
                RefreshData();
            }
        }

        public ListControl ParentList
        {
            get { return _parentList; }
            set
            {
                if (_parentList != null)
                {
                    _parentList.SelectedValueChanged -= ParentListItemsChanged;
                    _parentList.DataSourceChanged -= ParentListItemsChanged;
                }
                _parentList = value;
                _parentList.SelectedValueChanged += ParentListItemsChanged;
                _parentList.DataSourceChanged += ParentListItemsChanged;
                RefreshData();
            }
        }

        public bool AutoSelectSoloItem { get; set; }

        protected void ParentListItemsChanged(object sender, EventArgs e)
        {
            RefreshData();
        }

        protected object lastParentSelectedValue;

        public void RefreshData()
        {
            object parentSelectedValue = null;
            //  .SelectedValue property throws an exception
            //  if the underlying data source has changed
            //  and the SelectedIndex is invalid.
            try
            {
                parentSelectedValue = _parentList.SelectedValue;
            }
                // ReSharper disable EmptyGeneralCatchClause
            catch
                // ReSharper restore EmptyGeneralCatchClause
            { }

            int childSelectedIndex = -1;
            if (lastParentSelectedValue == parentSelectedValue)
            {
                childSelectedIndex = _childList.SelectedIndex;
            }
            lastParentSelectedValue = parentSelectedValue;

            if (parentSelectedValue != null && DynamicDataSource != null)
            {
                _childList.Enabled = true;
                var items = DynamicDataSource(_parentList.SelectedValue as TParentValue);
                _childList.DataSource = items;

                if (AutoSelectSoloItem && childSelectedIndex == -1 && items.Count == 1)
                {
                    _childList.SelectedIndex = 0;
                }
                else
                {
                    _childList.SelectedIndex = childSelectedIndex;
                }
            }
            else
            {
                _childList.DataSource = null;
                _childList.SelectedIndex = -1;
                _childList.Enabled = false;
            }
        }
    }
}