object reference problem, textbox, datagrid, clientID

[tigerjade]

It's me again. :/ I'm trying to get the ClientID of an object on the ItemDataBound event to attach to another object. When I run the code, I get the System.NullReferenceException error: Object reference not set to an instance of the object.

.aspx code:

<asp:TemplateColumn HeaderText="Return Date">
						<ItemTemplate>
							<asp:Label ID="dateLabel" Runat="server" Text='<%# DataBinder.Eval(Container.DataItem, "detReturnDateTime", "{0:D}")%>' />
						</ItemTemplate>
						<EditItemTemplate>
							<asp:TextBox ID="updateDateText" Runat="server" Font-Size="8pt" Text='<%# DataBinder.Eval(Container.DataItem, "detReturnDateTime", "{0:D}")%>' ReadOnly="True"></asp:TextBox><asp:HyperLink id="lbtnCalendar" runat="server" ImageUrl="images/calendar.gif"></asp:HyperLink>
						</EditItemTemplate>
					</asp:TemplateColumn>

.aspx.cs code:

protected void UserDetailsDataGrid_ItemDataBound(object sender, DataGridItemEventArgs e)
		{
			if (e.Item.ItemType == ListItemType.Item) 
			{
				TextBox udt = (TextBox)e.Item.FindControl("updateDateText");
				HyperLink calHL = e.Item.FindControl("lbtnCalendar") as HyperLink;
				calHL.NavigateUrl = "javascript:openWin('PopupCalendar.aspx?field=Form1" + udt.ClientID + "','newWin','width=250,height=290,toolbars=no,scrollbars=no,resizable=yes');";
			}
		}

What am I doing wrong this time?

Thanks!

tigerjade

"Always code as if the person who ends up maintaining your code will be a violent psychopath who knows where you live." -- Martin Golding

 

[tigerjade]

As usual, I get to my wits' end, post here, and then find an answer. I think my big screwup was in determining the index; I found this code:

		protected void UserDetailsDataGrid_ItemDataBound(object sender, DataGridItemEventArgs e)
		{
			if (e.Item.ItemType == ListItemType.EditItem) 
			{
				Int32 iLastCellIndex = e.Item.Cells.Count-1;
				String sTextBoxName = e.Item.Cells[iLastCellIndex].FindControl("updateDateText").ClientID;
				TextBox udt = e.Item.FindControl("updateDateText") as TextBox;
				HyperLink calHL = e.Item.FindControl("lbtnCalendar") as HyperLink;
				calHL.NavigateUrl = "javascript:openWin('PopupCalendar.aspx?field=Form1." + sTextBoxName + "','newWin','width=250,height=290,toolbars=no,scrollbars=no,resizable=yes');";
			}
		}

And it worked like a charm!

tigerjade

"Always code as if the person who ends up maintaining your code will be a violent psychopath who knows where you live." -- Martin Golding