c# - 如何使用 Asp.net 在树视图中动态添加根节点

Question

我想将 DataTable 绑定到 TreeView。我编写了以下代码。它目前正在工作，意味着它显示了 DataTable 的所有数据但没有根节点。

 List<DocumentData> lstData = GetSPDocuments();
    gvDocuments.DataSource = lstData;
    gvDocuments.DataBind();

    DataTable dt = ConvertToDataTable(lstData);

    TreeNode node1 = new TreeNode("Root");


    foreach (DataRow r in dt.Rows)
    {
        int nodeLvl = int.Parse(r["ID"].ToString());
        string nodeParent = "Folders";
        string nodeName = r["Title"].ToString();


        TreeNode tNode = new TreeNode(nodeName);

        ht.Add(nodeLvl.ToString() + nodeName, tNode);

        if (tvDocs.Nodes.Count == 0)
            tvDocs.Nodes.Add(tNode);
        else
        {
            nodeLvl--;
            tvDocs.Nodes.Add(tNode);               
        }
    }

如何在此处添加静态根节点？？？请帮忙！

Answer 1

Try this may be it can help you.

 protected void Page_Load(object sender, EventArgs e)
    {
        conStr = ConfigurationManager.ConnectionStrings["conString"].ConnectionString;
        conn = new OleDbConnection(conStr);
        BindTreeViewControl();
    }

    private void BindTreeViewControl()
    {
        try
        {
            DataSet ds = GetDataSet("Select ProductId,ProductName,ParentId from ProductTable");
            DataRow[] Rows = ds.Tables[0].Select("ParentId = 0"); 

            for (int i = 0; i < Rows.Length; i++)
            {
                TreeNode root = new TreeNode(Rows[i]["ProductName"].ToString(), Rows[i]["ProductId"].ToString());
                root.SelectAction = TreeNodeSelectAction.Expand;
                CreateNode(root, ds.Tables[0]);
                treeviwExample.Nodes.Add(root);
            }
        }
        catch (Exception Ex) { throw Ex; }
    }

    public void CreateNode(TreeNode node, DataTable Dt)
    {
        DataRow[] Rows = Dt.Select("ParentId =" + node.Value);
        if (Rows.Length == 0) { return; }
        for (int i = 0; i < Rows.Length; i++)
        {
            TreeNode Childnode = new TreeNode(Rows[i]["ProductName"].ToString(), Rows[i]["ProductId"].ToString());
            Childnode.SelectAction = TreeNodeSelectAction.Expand;
            node.ChildNodes.Add(Childnode);
            CreateNode(Childnode, Dt);
        }
    }
    private DataSet GetDataSet(string Query)
    {
        DataSet Ds = new DataSet();
        try
        {
            OleDbDataAdapter da = new OleDbDataAdapter(Query, conn);
            da.Fill(Ds);
        }
        catch (Exception dex) { }
        return Ds;
    }

and database structure for this is

Answer 2

// Suppress repainting the TreeView until all the objects have been created.
treeView1.BeginUpdate();

// Clear the TreeView each time the method is called.
treeView1.Nodes.Clear();

// create root node
TreeNode root = new TreeNode("Root");

// loop and add all child nodes to root node
foreach (DataRow r in dt.Rows)
{
    // create child node 
    // add to root node 
     root.Nodes.Add(child);
}

// add root node to tree view
treeView1.Nodes.Add(root);

// Begin repainting the TreeView.
treeView1.EndUpdate();

Answer 3

你有没有得到这个答案？你快到了。

TreeView控件的名称是什么？既然您从未说过，我正在使用treeView1，并修改了您的代码以包含以下内容：

private TreeView treeView1;

private void TreeView_DataBind() {

  treeView1.Nodes.Clear();

  List<DocumentData> lstData = GetSPDocuments();
  gvDocuments.DataSource = lstData;
  gvDocuments.DataBind();

  DataTable dt = ConvertToDataTable(lstData);

  TreeNode node1 = new TreeNode("Root");

  treeView1.Nodes.Add(node1); // this is the step you missed

  foreach (DataRow r in dt.Rows)
  {
    int nodeLvl = int.Parse(r["ID"].ToString());
    string nodeParent = "Folders";
    string nodeName = r["Title"].ToString();

    TreeNode tNode = new TreeNode(nodeName);

    ht.Add(nodeLvl.ToString() + nodeName, tNode);

    if (tvDocs.Nodes.Count == 0)
      tvDocs.Nodes.Add(tNode);
    else
    {
      nodeLvl--;
      tvDocs.Nodes.Add(tNode);               
    }
  }

  node1.Expand();

}

十分简单！