Question

I have a data-bound, templated control, and inside the templated area I create a control with an event handler, like so:

<tnl:DisplayTree ID="DisplayTree1" runat="server" KeyPropertyName="Id" 
ParentPropertyName="ParentDemographic" DataSourceID="DemographicObjectSource">
<ItemTemplate>
    <asp:CheckBox ID="DemogSelector" runat="server" OnCheckedChanged="DemogSelector_OnCheckedChanged" /> &nbsp;
    <asp:Label ID="InlineEditLabel" runat="server" Text='<%#DataBinder.Eval(Container.DataItem, "Name") %>'></asp:Label>
    </ItemTemplate>
</tnl:DisplayTree>

Within the event handler, I would like to be able to detect the Key of the item for which the control was created. For example:

protected void DemogSelector_OnCheckedChanged(object sender, EventArgs e)
{
    CheckBox selector = (CheckBox)sender;
    DisplayTree.TreeNode treeNode = (DisplayTree.TreeNode)selector.Parent.Parent.Parent.Parent;
    Label1.Text += (int)treeNode.Key + ", ";
}

As you can see, this approach requires close knowledge of the hierarchy within my DisplayTree.TreeNode class (i.e. I have to know that sender.Parent.Parent.Parent.Parent is where I’ll find the DisplayTree.TreeNode object). I would like to make it a bit more robust, so that if my TreeNode hierarchy changes or something, I can access the key without difficulty. What’s the best way for me to make this Key available from within the event handler?

Answer 1

Best way is to add a custom attribute to your checkbox

<asp:CheckBox ID="DemogSelector" runat="server" oncheckedchanged="DemogSelector_CheckedChanged" AutoPostBack="true" key='<%# Eval("Id") %>'/>

And then access it using

string key = (sender as CheckBox).Attributes["key"];