I have a TreeView As a control that the users select Node and the selectedNode text is written in a Textbox...

The problem i have if the user select time after time the same Node the Event - TreeView1_SelectedNodeChanged won't fire in the second time!!!

So how can this SelectedNodeChanged be fire eventhough the user selected the same Node?!

Well, the node has not changed, so you can't have the selectednodechanged event fire, but you can have an onclick event.  You might have to add it to each node as you bind your datasource or as you create it. 

 --JJ

Hi max,

You can attach a onclick event to full treeview and in javascript you can achieve what you want to do.

I dont know any way by which we can assign an eventhandler to each node, so i will suggest you to use javascript.

Add this in your page

<script type="text/javascript">

function client_OnTreeNodeChecked(event)

{ var TreeNode = event.srcElement || event.target ; // The clicked node

 document.getElementById('<%=YourTextBoxId.ClientID%>').value =TreeNode.nextSibling.title;

}

</script>

Add this in you code behind to attach this function with treeview click, in Page_Load,

TreeView1.Attributes.Add("OnClick", "client_OnTreeNodeChecked(event)");

Hope this works for you

It turns out there is no onclick event, but there is a navigateurl you can take advantage of:

 protected void TreeView1_TreeNodeDataBound(object sender, TreeNodeEventArgs e)
    {
        e.Node.NavigateUrl = "javascript:alert('" + e.Node.Text + "');";
    }

 Keep in mind, if you already have a navigateurl, you will have to modify the navigateurl in order to do both actions.  Here, all I am doing is alerting witht the text of the node, you can do any number of things including posting back to the server. 

--JJ

Huge thanks, maybe this will do the trick... but I still cant get it right (sorry but Im a novice). Is it possible to execute server side functions width javascript directly? Should I create a hidden button and execute that button from javascript code (but how do I pass parameters this way)? Or should I use querystrings? 

Hi,

This is quite a recurrent requirement posted on these forums and no workable solution has yet been posted( at least in my knowledge) so i thought of giving it a try. Think i have arrived at a solution:

1) put a hidden field in the .aspx page as:

----------------------------

<asp:HiddenField ID="hdnTreeSelectedNodeValue" runat="server" />

---------------------------

2) code behind should look like:

--------------------------------------- 

 protected void Page_Load(object sender, EventArgs e)
    {
       
        if (IsPostBack)
        {
            //getting the value of the hidden variable that holds the value
            //of selected node, this variable is a part of treeview design
            string TvSelNodeHdnFldId = TreeView1.ClientID + "_SelectedNode";
            string TvSelNodeVal = Request[TvSelNodeHdnFldId].ToString();

            if (hdnTreeSelectedNodeValue.Value != "" && (hdnTreeSelectedNodeValue.Value == TvSelNodeVal))
            {
                //same treenode click, selectednodechanged event will not fire
                //so execute our treenode click handler
                TreeNodeClickHandler();
            }
            else
            {
                //different node click, selectednodechanged event will not fire
                //so only set the hidden variable value
                hdnTreeSelectedNodeValue.Value = TvSelNodeVal;
            }
        }
       
    }

 //handler for SelectedNodeChanged event

 protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        TreeNodeClickHandler(); //just call the helper function here
    }

    //helper function having code to be executed on the click of a treenode
    private void TreeNodeClickHandler()
    {
        TreeNode selectedNode = TreeView1.SelectedNode;

        //play with selected node
        TextBox1.Text = selectedNode.Text;
    }

------------------------------------

The idea is to have a helper function that would be made to execute on the click of a treenode(whether re-click or not). A couple of hidden fields are put on the page when a tree view is rendered, one of those keep the track of the selected node. I used it(by retrieving its value from the request collection) to check if the an already selected node is clicked or not.

Hope this helps. 

Gah, I still have a problem.  If there is other buttons and stuff on the same page, the TreeNodeClickHandler allways executes. How do I know if it is a second click in my treeview or if it is a click from somewhere else? What I am trying to achive is a menu width some filter functions, for example one dropdownlist that contains sortorder and it is triggered with a click in my treeview. So if I change the sortorder and click the same treenode again nothing will happen as default. Maybe the treeview wasnt supposed to be used liked this, but it really works great if it wasn't for this second click problem...

Anyway, I do have a solution of my own but I guess it contains some awful code... here is my solution, what do you ppl think about it?

First I put one invisible button and a textbox on the page.

 Then I add a javascript in the navigateurl on every node:

In this funkction I can get all values I need, what node was clicked and all values from my textbox and dropdownlists...

maxald:

Gah, I still have a problem.  If there is other buttons and stuff on the same page, the TreeNodeClickHandler allways executes. How do I know if it is a second click in my treeview or if it is a click from somewhere else?

Guys, sorry for that silly mistake, i didn't test the code properly. Thanks to maxlad for pointing it out. I'm posting the revised solution here,

do let me know how it works:

1) put a hidden field in the .aspx page as:

----------------------------

<asp:HiddenField ID="hdnTreeSelectedNodeValue" runat="server" />

---------------------------

2) code behind should look like:

---------------------------------------  

 protected void Page_Load(object sender, EventArgs e)
    {
        TextBox1.Text = "";

        if (IsPostBack)
        {
            //getting the value of the hidden variable that holds the value
            //of selected node, this variable is a part of treeview design
            string TvSelNodeHdnFldId = TreeView1.ClientID + "_SelectedNode";
            string TvSelNodeVal = Request[TvSelNodeHdnFldId].ToString();
            string postBackControlId = Request["__EVENTTARGET"].ToString(); //this tells you if treenode has caused a postback
             
           if ((hdnTreeSelectedNodeValue.Value != "") && (hdnTreeSelectedNodeValue.Value == TvSelNodeVal) && (postBackControlId == TreeView1.UniqueID))
            {
                //same treenode click, selectednodechanged event will not fire
                //so execute our treenode click handler
                TreeNodeClickHandler();
            }
            else
            {
                //different node click, selectednodechanged event will fire
                //so only set the hidden variable value
                hdnTreeSelectedNodeValue.Value = TvSelNodeVal;
            }
        }
        
    }

    
    protected void TreeView1_SelectedNodeChanged(object sender, EventArgs e)
    {
        TreeNodeClickHandler();
    }

    //helper function having code to be executed on the click of a treenode
    private void TreeNodeClickHandler()
    {
        TreeNode selectedNode = TreeView1.SelectedNode;

        //play with selected node
        TextBox1.Text = selectedNode.Text;
    }

-----------------------------------------

Hope this works fine. 

A few things of note.

1. When you create javascript that references a server control (aspx control with runat=server) always create the script in codebehind during page load or another page initialization event.  Use controlname.ClientId to get the name of the control as seen on the final page (the name that you can use in javascript).  Then register the script using registerclientscriptblock so it can be used.
2. If you want to postback from javascript use a page postbackreference created in code behind in your javascript.
3. Research __EventTarget and __EventArgument to find out which control caused the postback on your page.

I'm not sure if my situtation is exactly the same, but I think it is, and my solution is a bit simpler.  First of all, my scenario is that I provide users with a list of categories, they click one and I switch the view on the page and provide them with the items in the selected category.  The results view has a "Return to Categories" linkbutton on it that simply changes the view back to the category tree.  The problem I was having is that the user could click any other category and get the appropriate results, but they could not click the original category again.  So I fixed the problem by resetting the selected node in the SelectedNodeChanged event handler:

protected void CategoryTree_SelectedNodeChanged(Object sender, EventArgs e){

TreeNode node = CategoryTree.SelectedNode;

//allows for backing up then clicking the node again.

Thanks pushp_aspnet ,  thats was a perfect solution to capturing the onclick of the TreeView when it has not changed.  Good work!!!