using System.Data;
using System.Web.UI.WebControls;
/// summary>
/// 根據DataTable生成下拉列表樹
/// /summary>
public class DropDownListHelp
{
private string gridline;
private DataTable dt;
public DropDownListHelp()
{
//
//TODO: 在此處添加構造函數邏輯
//
}
/// summary>
/// 根據Datatable生成樹形下拉菜單
/// /summary>
/// param name="datatable">/param>
/// param name="parentKeyField">上級節點關鍵字段/param>
/// param name="parentKey">上級節點值/param>
/// param name="keyField">本節點關鍵字段/param>
/// param name="sortString">排序字符串/param>
/// param name="ddl">DownList/param>
public void createDropDownTree(DataTable datatable, string parentKeyField, string parentKey, string keyField, string textField, string sortString, DropDownList ddl)
{
dt = datatable;
ddl.Items.Add(new ListItem("", ""));
addChildItems(parentKeyField, parentKey, keyField, textField, sortString, ddl);
}
/// summary>
/// 遞歸生成樹節點
/// /summary>
/// param name="parentKeyField">上級節點關鍵字段/param>
/// param name="parentKey">上級節點值/param>
/// param name="keyField">本節點關鍵字段/param>
/// param name="sortString">排序字符串/param>
/// param name="ddl">DownList控件/param>
/// returns>/returns>
private void addChildItems(string parentKeyField, string parentKey, string keyField, string textField, string sortString, DropDownList ddl)
{
DataView dv = new DataView(dt, parentKeyField + "='" + parentKey + "'", sortString, DataViewRowState.CurrentRows);
int a = dv.Count;
if (dv.Count == 0)
{
return;
}
for (int i = 0; i a; i++)
{
gridline = "";
dv.RowFilter = parentKeyField + "='" + parentKey + "'";
dv.Sort = sortString;
getTreeLine(parentKeyField, dv[i][parentKeyField].ToString(), keyField, dv[i][keyField].ToString(), sortString);
dv.RowFilter = parentKeyField + "='" + parentKey + "'";
dv.Sort = sortString;
ddl.Items.Add(new ListItem(gridline + (i == a - 1 ? "┗" : "┣") + dv[i][textField].ToString(), dv[i][keyField].ToString()));
addChildItems(parentKeyField, dv[i][keyField].ToString(), keyField, textField, sortString, ddl);
}
dv.Dispose();
}
/// summary>
/// 回溯生成樹的連接線
/// /summary>
/// param name="parentKeyField">上級節點關鍵字段/param>
/// param name="parentKey">上級節點值/param>
/// param name="keyField">本節點關鍵字段/param>
/// param name="nodeKey">本節點值/param>
/// param name="sortString">排序字符串/param>
/// returns>/returns>
private void getTreeLine(string parentKeyField, string parentKey, string keyField, string nodeKey, string sortString)
{
//選擇父層節點
DataView dv = new DataView(dt, keyField + "='" + parentKey + "'", sortString, DataViewRowState.CurrentRows);
if (dv.Count > 0)
{
//選擇父節點同級節點
dv.RowFilter = parentKeyField + "='" + dv[0][parentKeyField].ToString() + "'";
dv.Sort = sortString;
for (int j = 0; j dv.Count; j++)
{
if (dv[j][keyField].ToString() == parentKey)
{
if (j == dv.Count - 1)
{
gridline = "　" + gridline;
}
else
{
gridline = "┃" + gridline;
}
}
}
getTreeLine(parentKeyField, dv[0][parentKeyField].ToString(), keyField, dv[0][keyField].ToString(), sortString);
}
dv.Dispose();
}
}

DropDownListHelp ddlHelper = new DropDownListHelp();
ddlHelper.createDropDownTree(dt, "parentID", "1", "ID","Text", "Text asc", DropDownList1);