ASP.NET TreeView and Selecting the Selected Node

Question

How do I capture the event of the clicking the Selected Node of a TreeView? It doesn\'t fire the SelectedNodeChanged since the selection has obviously not c

Answer 1

i have a problem look like but i solved it !

in server side code :

    protected void MainTreeView_SelectedNodeChanged(object sender, EventArgs e)
    {
        ClearTreeView();
        MainTreeView.SelectedNode.Text = "<span class='SelectedTreeNodeStyle'>" + MainTreeView.SelectedNode.Text + "</span>";
        MainTreeView.SelectedNode.Selected = false;

    }

    public void ClearTreeView()
    {
         for (int i = 0; i < MainTreeView.Nodes.Count; i++)
        {
            for(int j=0;j< MainTreeView.Nodes[i].ChildNodes.Count;j++)
            {
                ClearNodeText(MainTreeView.Nodes[i].ChildNodes[j]);
            }
            ClearNodeText(MainTreeView.Nodes[i]);
        }
    }

    public void ClearNodeText(TreeNode tn)
    {
        tn.Text = tn.Text.Replace("<span class='SelectedTreeNodeStyle'>", "").Replace("</span>", "");
    }

in client side code :

 <style type="text/css">
     .SelectedTreeNodeStyle { font-weight: bold;}
 </style>

Answer 2

You can always use the MouseDown or MouseUp event and check to see if it the selected node.

Answer 3

When you're adding nodes to the tree in the _TreeNodePopulate() event, set the .SelectionAction property on the node.

TreeNode newCNode;
newCNode = new TreeNode("New Node");

newCNode.SelectAction = TreeNodeSelectAction.Select;

//now you can set the .NavigateUrl property to call the same page with some query string parameter to catch in the page_load()

newCNode.NavigateUrl = "~/ThisPage.aspx?args=" + someNodeAction

RootNode.ChildNodes.Add(newCNode);

Answer 4

I use the ShowCheckBox property and the Checked property to "highlight" the selected item. When the SelectedNodeChanged event raises:

1. I set to false the ShowCheckBox property and the Checked property for the old selected one and I set to true the ShowCheckBox property and the Checked property for the new selected one.
2. I use the selected node for any action
3. Finally, I unselect the selected item: myTreeView.SelecteNode.Selected = false

Answer 5

After a somewhat lengthy period, I have finally had some time to look into how to subclass the TreeView to handle a Selected Node being clicked.

Here is my solution which exposes a new event SelectedNodeClicked which you can handle from the Page or wherever. (If needed it is a simple task to refactor into C#)

Imports System.Web.UI
Imports System.Web


Public Class MyTreeView
  Inherits System.Web.UI.WebControls.TreeView

  Public Event SelectedNodeClicked As EventHandler

  Private Shared ReadOnly SelectedNodeClickEvent As Object

  Private Const CurrentValuePathState As String = "CurrentValuePath"

  Protected Property CurrentValuePath() As String
    Get
      Return Me.ViewState(CurrentValuePathState)
    End Get
    Set(ByVal value As String)
      Me.ViewState(CurrentValuePathState) = value
    End Set
  End Property

  Friend Sub RaiseSelectedNodeClicked()

    Me.OnSelectedNodeClicked(EventArgs.Empty)

  End Sub

  Protected Overridable Sub OnSelectedNodeClicked(ByVal e As EventArgs)

    RaiseEvent SelectedNodeClicked(Me, e)

  End Sub

  Protected Overrides Sub OnSelectedNodeChanged(ByVal e As System.EventArgs)

    MyBase.OnSelectedNodeChanged(e)

    ' Whenever the Selected Node changed, remember its ValuePath for future reference
    Me.CurrentValuePath = Me.SelectedNode.ValuePath

  End Sub

  Protected Overrides Sub RaisePostBackEvent(ByVal eventArgument As String)

    ' Check if the node that caused the event is the same as the previously selected node
    If Me.SelectedNode IsNot Nothing AndAlso Me.SelectedNode.ValuePath.Equals(Me.CurrentValuePath) Then
      Me.RaiseSelectedNodeClicked()
    End If

    MyBase.RaisePostBackEvent(eventArgument)

  End Sub

End Class

Answer 6

Easiest way - if it doesn't interfere with the rest of your code - is to simply set the node as not selected in the SelectedNodeChanged method.

protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e){
  // Do whatever you're doing
  TreeView1.SelectedNode.Selected = false;
}