winform实现下拉控件的无限级联动(DevExpress版)

private List<TradeTypeEntity> trades = null;//存储数据
        private List<LookUpEdit> ctl_dic = new List<LookUpEdit>();//存储控件
        private TradeTypeEntity empty_model = new TradeTypeEntity() { PT_TradeID = null, PT_TradeName = "请选择" };//空数据的示例

/// <summary>
        /// 加载行业类型（仅父类）
        /// </summary>
        public void InitTrade()
        {
            trades = CacheStrategy.Instance.GetObject(CacheKey.Trades) as List<TradeTypeEntity>;
            var data = (from v in trades where v.PT_ParentID.Equals("0") select v).ToList();
            LookUpEdit ctl = PrepareCtl(data);
            ctl.EditValue = null;
            ctl.EditValueChanged += new EventHandler(ctl_EditValueChanged);
            ctl_dic.Insert(0, ctl);
            ShowCtls();
        }
        /// <summary>
        /// 加载行业类型
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        public void InitTrade(string trade_code)
        {
            trades = CacheStrategy.Instance.GetObject(CacheKey.Trades) as List<TradeTypeEntity>;
            var target = trades.Single(v => { return v.PT_TradeCode.Equals(trade_code); });
            CreateCtls(target);
            ShowCtls();
        }

/// <summary>
        /// 创建控件,用到了递归
        /// </summary>
        /// <param name="trade_code"></param>
        private void CreateCtls(TradeTypeEntity target)
        {
            var data = (from v in trades where v.PT_ParentID.Equals(target.PT_ParentID) select v).ToList();
            LookUpEdit ctl = PrepareCtl(data);
            ctl.EditValue = target.PT_TradeID;
            ctl.EditValueChanged += new EventHandler(ctl_EditValueChanged);
            ctl_dic.Insert(0, ctl);
            if (target.PT_ParentID.Equals("0"))
            {
                return;
            }
            var target_temp = trades.Single(v => { return v.PT_TradeID.Equals(target.PT_ParentID); });
            CreateCtls(target_temp);
        }

/// <summary>
        /// 准备控件
        /// </summary>
        /// <param name="ctl"></param>
        /// <param name="data"></param>
        private LookUpEdit PrepareCtl(List<TradeTypeEntity> data)
        {
            data.Insert(0, empty_model);
            LookUpEdit ctl = new LookUpEdit();
            ctl.Properties.PopupWidth = 50;
            ctl.Properties.DataSource = data;
            ctl.Properties.ShowFooter = false;
            ctl.Properties.ShowHeader = false;
            ctl.Properties.PopupFormMinSize = new System.Drawing.Size(50, 0);
            ctl.Properties.DisplayMember = "PT_TradeName";
            ctl.Properties.ValueMember = "PT_TradeID";
            ctl.Properties.Columns.Add(new LookUpColumnInfo("PT_TradeName"));
            ctl.Properties.AllowNullInput = DevExpress.Utils.DefaultBoolean.True;
            ctl.Properties.NullText = "请选择";
            return ctl;
        }

/// <summary>
        /// 选择项变更事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void ctl_EditValueChanged(object sender, EventArgs e)
        {
            LookUpEdit sourceCtl = (LookUpEdit)sender;
            int index = ctl_dic.IndexOf(sourceCtl);
            ctl_dic.RemoveRange(index + 1, ctl_dic.Count - index - 1);
            if (sourceCtl.EditValue == null)
            {
                ShowCtls();
                return;
            }
            var data = (from v in trades where v.PT_ParentID.Equals(sourceCtl.EditValue) select v).ToList();
            if (data.Count > 0)
            {
                LookUpEdit ctl = PrepareCtl(data);
                ctl.EditValue = null;
                ctl.EditValueChanged += new EventHandler(ctl_EditValueChanged);
                ctl_dic.Add(ctl);
            }
            ShowCtls();
        }

/// <summary>
        /// 显示控件
        /// </summary>
        private void ShowCtls()
        {
            ctlTable.Controls.Clear();
            for (int i = 0; i < ctl_dic.Count; i++)
            {
                ctlTable.Controls.Add(ctl_dic[i], i, 0);
            }
        }

/// <summary>
        /// 获取选中的值
        /// </summary>
        /// <returns></returns>
        public string GetSelectedID()
        {
            if (ctl_dic.First().EditValue == null)
            {
                return string.Empty;
            }
            else if (ctl_dic.Last().EditValue == null)
            {
                return ctl_dic[ctl_dic.Count - 2].EditValue as string;
            }
            return ctl_dic.Last().EditValue as string;
        }
        /// <summary>
        /// 获取选中的文本
        /// </summary>
        /// <returns></returns>
        public string GetSelectedText()
        {
            if (ctl_dic.First().Text.Equals("请选择"))
            {
                return string.Empty;
            }
            else if (ctl_dic.Last().Text.Equals("请选择"))
            {
                return ctl_dic[ctl_dic.Count - 2].Text;
            }
            return ctl_dic.Last().Text;
        }