Unable to cast an object of type System.Web.UI.WebControls.TreeNode to Custom node

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Hi,

I have a custom class 'Node' inheriting the System.Web.UI.WebControls.TreeNode class. On the SelectedNodeChanged event of the treeview, I am trying to change the type of Treeview.SelectedNode to the custom type, Node. While performing this type casting I am getting the InvalidCastException.

********************EDIT**********************
The SelectedNodeChanged event HANDLER is defined as follows

protected void tvTreeview_SelectedNodeChanged(object sender, EventArgs e)<br />
{<br />
   TreeNode tn = tvTreeview.SelectedNode;<br />
   Node selectednode = (Node)tn;          //Exception thrown at this line<br />
}<br />

**********************************************

Since 'e' is of type EventArgs, there are no properties defined for it.

Can anybody please help me with this problem?

Its urgent!!

Posted 11-Jul-11 2:07am

maithilym

Updated 11-Jul-11 23:15pm

v5

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Apfelmuuus 11-Jul-11 8:16am

Please show the code how you want to change the type by typecasting. this would help more then tvTreeview_SelectedNodeChanged event!

maithilym 11-Jul-11 8:22am

I have updated the ques with appropriate code

#realJSOP 11-Jul-11 8:30am

DO NOT update the question with your answer. Post a solution instead. I removed your change.

Apfelmuuus 11-Jul-11 8:35am

It wasnt his answer! It was his problem code you have deleted! Can you undo this?

Sergey Alexandrovich Kryukov 11-Jul-11 22:03pm

First, what you call an event is not an event. Hope it's a handler. I'm still not sure where is the problem. Could you post a code sample. Simple one, please, not all your code. Include: 1) setting a handler (+= operation), 2) handler; 3) code where you cast.
--SA

maithilym 12-Jul-11 0:02am

I have edited the question with the code block where i am trying to type-cast. Since this is an aspx page i did not have to set the handler explicitly. I have just declared it in the Event properties of the TreeView control, as

<asp:TreeView ID="tvController" runat="server" ExpandDepth="0" OnTreeNodePopulate="tvController_TreeNodePopulate"
PathSeparator="\" OnSelectedNodeChanged="tvController_SelectedNodeChanged">

Currently I am trying to work with the solution provided by Apfelmuuus. If I am able to get the desired results successfully, I will update the post accordingly.

Thanks for your responses!

2 solutions

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Apfelmuuus · Answer 1 · 2011-07-11T02:30:00

Solution 2

No Way! You cant typecast a reference to a TreeNode object to a Node object. You can only typecast a TreeNode reference that refers to a Node object. For Example:

TreeNode tn = new Node();
Node n = (Node) tn;

So make sure that tn refers to a Node object.

Regards.

Posted 11-Jul-11 2:30am

Apfelmuuus

Comments

Sergey Alexandrovich Kryukov 11-Jul-11 21:59pm

Isn't it what OP does, according to the description? I think the problem is incomplete question. We need OP's code sample.
--SA

#realJSOP · Answer 2 · 2011-07-11T02:10:00

Solution 1

You probably need to cast the sender to the appropriate type instead.

EDIT ==================

You still have to cast the sender to get the selected node:

C#

Treeview tree = sender as TreeView;
Node node = tree.SelectedNode as Node;

Posted 11-Jul-11 2:10am

#realJSOP

Updated 11-Jul-11 2:29am

v2

Comments

maithilym 11-Jul-11 8:13am

Thanks for your instant reply.
But this option does not work as sender is of the type TreeView. Cannot be cast into Node.

#realJSOP 11-Jul-11 8:31am

See my updated solution.