Chanage button visibility if the button is outside of the UpdatePanel

Hello everyone,

Here is my scenario, and my problem.

I have a grid inside an UpdatePanel_1. The grid is populated after a Search button inside another UpdatePanel_0 is clicked (this is actually an user control and UpdatePanel_0 is inside the user control). This works fine.

I want to provide an Export button which exports the data from the grid to Excel, but want to show it only if the grid has any records.

If I add the button to UpdatePanel_1 the visibility toggling works fine, but when I click on the button I get the nasty message:

"Sys.WebForms.PageRequestManagerParserErrorException: The message received from the server could not be parsed. Common causes for this error are when the response is modified by calls to Response.Write(), Response filters, HTTP modules, or trace is enabled... "

And of course, I am using Response.Write for the Export of the grid to Excel.

If I put the Export button out of UpdatePanel_1, the Export works fine, but I cannot find a way to toggle the visiblity of the button. I set the visibility in the code behind when the grid has some records, but it doesn't seem to work (probably because the button is outside of the UpdatePanel_1).

What should I do to make the Exprot work and the button to appear only when I want it?

Thank you!

You could add the button to the UpdatePanelGridView and add an async trigger for the gridview databind event. So on databind, if gridview is empty your button will not show.

Hi Denis,

Thank you for your reply.

Setting the visibility of the button is not a problem when the button is inside the UpdatePanel. The problem in this case is that Export to Excel, which has to happen when the user pushes the button, doesn't work because of the error mentioned above (and the reason for the error is the Response.Write statement in the function below).

If I put the button out of the UpdatePanel, the Export to Excel works, but I have no control over the button's visibility, because it depends on the GridView records, which is inside an UpdatePanel.

Here is the function I use for the Export:

Public Sub ExportGridToExcel(ByVal grvBusinessAs GridView,ByVal pageAs Page,ByVal fileNameAs String)If grvBusiness.Rows.Count.ToString + 1 < 65536Then Dim twAs New StringWriter()Dim hwAs New System.Web.UI.HtmlTextWriter(tw)Dim frmAs HtmlForm =New HtmlForm() page.Response.ContentType ="application/vnd.ms-excel" page.Response.AddHeader("content-disposition","attachment;filename=" & fileName &".xls") page.Response.Charset ="" page.EnableViewState =False page.Controls.Add(frm) frm.Controls.Add(grvBusiness) frm.RenderControl(hw) page.Response.Write(tw.ToString()) page.Response.End()End If End Sub

I am still new to AJAX so little things like this are not easy to solve.