动态TreeView的使用

照着例子写了一个，发现不会动态添加。看看微软说明
http://msdn2.microsoft.com/zh-cn/library/system.web.ui.webcontrols.treenode.populateondemand(VS.80).aspx
需要TreeNode.PopulateOnDemand=true
但是第一个Node需要手工添加，然后设置PopulateOnDemand=true
    protected void TreeView1_TreeNodePopulate(object sender, TreeNodeEventArgs e)
    {
        if (e.Node.ChildNodes.Count == 0)
        {
            if (e.Node.Depth == 0)
            {
                FillBom(e.Node);
            }
            else
            {
                FillBomDetail(e.Node);
            }
        }

    }
    void FillBom(TreeNode node)
    {
        string ID = node.Value;
        BOMTableAdapters.BomModelTableAdapter oAdapter = new BOMTableAdapters.BomModelTableAdapter();
      
        BOM.BomModelDataTable oBomTable=oAdapter.GetData();

        if (oBomTable.Rows.Count > 0)
        {
            foreach (DataRow row in oBomTable.Rows)
            {
                TreeNode newNode = new TreeNode(row["model"].ToString(), row["model"].ToString());
                newNode.PopulateOnDemand = true;
                newNode.SelectAction = TreeNodeSelectAction.None;
                node.ChildNodes.Add(newNode);
            }
        }
    }
    void FillBomDetail(TreeNode node)
    {
        string ID = node.Value;
        BOMTableAdapters.BomModelItemTableAdapter oAdapter = new BOMTableAdapters.BomModelItemTableAdapter();
       
        BOM.BomModelItemDataTable oBomTable = oAdapter.GetDataByModel(ID);

        if (oBomTable.Rows.Count > 0)
        {
            foreach (DataRow row in oBomTable.Rows)
            {
                TreeNode newNode = new TreeNode(row["code"].ToString(), row["code"].ToString());
                newNode.PopulateOnDemand = true;
                newNode.SelectAction = TreeNodeSelectAction.None;
                node.ChildNodes.Add(newNode);
            }
        }