Treeview TreeNodePopulate event.

I have recently installed the AJAX Beta 2 Extensions having used the ATLAS CTP. Having installed it I removed the DLLs from the Bin directory. On two of my pages in the application I am using the Treeview controls which only populate child nodes when each of the parent nodes are clicked on. On one page this the treeview works fine and populates on demand -

1protected void ATreeview_TreeNodePopulate(object sender, TreeNodeEventArgs e)
2 {
3switch (e.Node.Depth)
4 {
5case 0:
6break;
7case 1:
8 PopulateTreeview(e.Node);
9break;
10 }
11 }

The PopulateTreeview method takes the node that should be populated (which for e.g. is the Category) and creates all the product nodes. At the moment the TreenodePopulate event does nothing as I just want to see whether it actually raises the event. When I discovered the problem I took out all the code in this event. The code at the moment is as follows:

1protected void ATreeview_TreeNodePopulate(object sender, TreeNodeEventArgs e)
2 {
3 lblMessage.Text ="inside the treenode populate " + e.Node.Depth.ToString();
4 lblMessage.Visible =true;
5 }

When I debug this and expand a node I get the following error:

"Microsoft JScript runtime error: 'ctl00_ContentPlaceHolder1_tvUsersNoGroup_Data' is undefined" - I have no choice but to press Break and stop the application from running. In the IDE it just highlights this line TreeView_PopulateNode(ctl00_ContentPlaceHolder1_ATreeview_Data,1,ctl00_ContentPlaceHolder1_ATreeviewn1,ctl00_ContentPlaceHolder1_ATreeviewt1,null,'t','A Category','TopNode\\3016','f','','tf')

The design source code is as follows:

<asp:UpdatePanel ID="upUsers" runat="server"> <ContentTemplate> <table border="0" class="report_treeview"> <tr style="background-color:#6178BE; color: #FFFFFF;font-weight:bold; font-size:80%;text-align:center;"> <td>Users not in selected security group</td> <td><asp:DropDownList ID="ddSecurity" runat="server" AppendDataBoundItems="True" AutoPostBack="true" OnSelectedIndexChanged="ddSecurity_SelectedIndexChanged"> <asp:ListItem Selected="True" Text="Please select a security group" Value="0"></asp:ListItem> </asp:DropDownList></td> <td>Users in selected security group</td> </tr> <tr> <td style="vertical-align: top; width: 300px; text-align:left;"> <asp:TreeView id="ATreeview" runat="server" showlines="true" visible="false" OnTreeNodePopulate="tvUsersNoGroup_TreeNodePopulate"></asp:TreeView> </td> <td style="border-right: solid 1px #DDDDDD;border-left: solid 1px #DDDDDD;text-align:center;"> <asp:Button ID="btnAddUser" runat="server" Text=">>" CssClass="option_button" OnClick="btnAddUser_Click" ToolTip="Add selected users." /> <p /> <p /> <asp:Button ID="btnRemoveUser" runat="server" Text="<<" CssClass="option_button" OnClick="btnRemoveUser_Click" ToolTip="Remove selected users." /> </td> <td style="vertical-align: top; width: 300px; text-align:left;"> <asp:Label ID="lblStatus" runat="server"></asp:Label></td> </tr> </table> <p /><asp:Label ID="lblMessage" runat="server" CssClass="labelStatus"></asp:Label> </ContentTemplate> </asp:UpdatePanel>

Anyone else come across this problem? Why is my other page fine and this page is throwing this error?

I did have something like this. I would get an error on the source code saying it the object was undifined when it was trying to put the tooltip on the treenode. To 'fix' it I turned off script debuging on my browser, and it went away.

It may be something to try

Eric Wild

Thanks for the suggestion but I don't think that the problem can be solved by suppressing the errors from the browser.

What I would like to know is if other people have had the same problems as myself.

Is this a problem with the AJAX Beta 2? or my silly code?

I am encountering this issue right now and know it is related to the Visible="false" on the TreeView.

I'm using RC1 and have a Button in an UpdatePanel and a TreeView in another UpdatePanel. The TreeView has it's Visible property = "false".

When the Button is clicked, it sets TreeView's Visible="true".

At this point, if you try to Expand a TreeView Node, it will come back with that same debugging trap you encountered. I tried using Fiddler to see if it passed anything, but it didn't.

You could either keep the TreeView's Visible property = "true" from the start or set the TreeView's EnableClientScript="false".

I think this deserves a bump and hope someone can further explain why and perhaps offer a workaround because the concept that the TreeView only populates its expanding Node is very nice.

Nathan