Why is the column disappearing?

MichSm · Apr 28, 2012

Hi, I am building a DataGrid with Template Columns which are dynamically added to a DataGrid in the Page_Load subroutine. The dynamic columns work fine when the page is first loaded, and also when the DataGrid goes into Edit Mode, but once in EditMode, as soon as I click on either the "Save" button, or the Button (or LinkButton) in my EditItemTemplate, then entire DYNAMIC Template Column simply disappears - although the DataGrid as a whole is STILL in Edit Mode. Now clicking on any of these buttons is firing the Page_Load subroutine (I even put a PageLoadCounter into the code to check!), but for some reason, the code within Page_Load that creates the template column STOPS working - and I have no idea why. Would really appreciate anyone telling me what's going on! Thanks, JON ++++++++++++++++++++++++++++++++++++++++++++++++++ ++++ MAIN DATAGRID PAGE (the EditItemTemplate is in a separate ascx file, see below): ++++++++++++++++++++++++++++++++++++++++++++++++++ ++++ <%@ Page Language="VB" Debug="true" %> <%@ Import Namespace="System.Data" %> <%@ Import Namespace="System.Data.Oledb" %> <script language="VB" runat="server"> Dim objConn as New OleDbConnection ( ConfigurationSettings.AppSettings("ConnectionString") ) Dim ds as Dataset = New DataSet() Dim objAdapter as New OleDbDataAdapter ( "SELECT * FROM tblItems WHERE ItemID = 1;", objConn ) '************************************************* ******************************** 'This is modified code from the section ' "Creating Templates Programmatically in the DataGrid Control", from URL: 'http://msdn.microsoft.com/library/default.asp?url=/library/en-us/ 'dv_vstechart/html/vbtchcreatingwebservercontroltemplatesprogrammatic ally.asp '************************************************* ******************************** Sub Page_Load(sender as object, e as eventargs) objConn.Open() objAdapter.Fill(ds, "tblItems") dg.DataSource = ds dg.DataMember = "tblItems" Dim tc1 As New TemplateColumn() tc1.HeaderTemplate = New DataGridTemplate(ListItemType.Header, "Column1") tc1.ItemTemplate = New DataGridTemplate(ListItemType.Item, "Column1") 'ADD THE ASCX EDIT_ITEM_TEMPLATE FILE tc1.EditItemTemplate = Page.LoadTemplate("Example_EditItemTemplate.ascx") tc1.FooterTemplate = New DataGridTemplate(ListItemType.Footer, "Column1") dg.Columns.Add(tc1) '*** just to check that Page_Load is really firing on the button clicks lbPageLoadCounter.Text = ViewState("iPageLoadCounter") ViewState("iPageLoadCounter") = ViewState("iPageLoadCounter") + 1 If Not Page.IsPostBack Then ViewState("iPageLoadCounter") = 1 lbPageLoadCounter.Text = ViewState("iPageLoadCounter") dg.Databind() End If End Sub sub dg_edit(sender as object, e as DataGridCommandEventArgs) dg.edititemindex = e.item.itemindex dg.databind() end sub sub dg_cancel(sender as object, e as DataGridCommandEventArgs) dg.edititemindex = -1 dg.databind() end sub sub dg_update(sender as object, e as DataGridCommandEventArgs) 'Put an update function here end sub sub dg_command(sender as object, e as DataGridCommandEventArgs) 'The buttons will do something here end sub Private Class DataGridTemplate Implements ITemplate Dim templateType As ListItemType Dim columnName As String Sub New(ByVal type As ListItemType, ByVal ColName As String) templateType = type columnName = ColName End Sub Sub InstantiateIn(ByVal container As Control) Implements ITemplate.InstantiateIn Dim lc As New Literal() Select Case templateType Case ListItemType.Header lc.Text = "Header" container.Controls.Add(lc) Case ListItemType.Item lc.Text = "Item " & columnName container.Controls.Add(lc) Case ListItemType.EditItem Dim tb As New TextBox() tb.Text = "" container.Controls.Add(tb) Case ListItemType.Footer lc.Text = "Footer" container.Controls.Add(lc) End Select End Sub End Class </script> <html> <body> Page_Load has fired this often: <asp:Label id="lbPageLoadCounter" runat="server" /> <form runat="server" name="form1" id="form1"> <asp

ataGrid id="dg" runat="server" AutoGenerateColumns="False" OnEditCommand="dg_edit" OnCancelCommand="dg_cancel" OnUpdateCommand="dg_update" OnItemCommand="dg_command" > <Columns> <asp:editcommandcolumn HeaderText="EDIT" edittext="Edit" CancelText="Cancel" UpdateText="Save" /> <asp:boundcolumn HeaderText="Test Non-Dynamic BoundColumn" DataField="ItemID" /> </Columns> </asp:dataGrid> </form> </body></html> __________________________________________________ ____________________________ CODE FOR "Example_EditItemTemplate.ascx": <%@ Control Language="VB" %> ItemTitle: <asp:Textbox id="tbItemTitle" runat="server" /> ItemRating: <asp:TextBox id="tbItemRating" runat="server" /> <asp:LinkButton id="lbtExampleLinkButton" runat="server" Text="ExampleLinkButton" /> <asp:Button id="btExampleButton" runat="server" Text="ExampleButton" />

Why is the column disappearing?

MichSm

New Member