Question

I have a simple class inheriting RadGrid. I am adding a button to the RadGrid and a Click Event handler to that button. The button is correctly added in the required position and the click event handler is firing, but radGrid.ExportToExcel() is not doing anything. In fact, upon click and when page posts back, the button disappears. Why is this happening?

I tried to add the button control to the Page.Form control collection, but still nothing happens.

[ToolboxData("<{0}:RadGridDp runat=server></{0}:RadGridDp>")]
public class RadGridDP : RadGrid
{
    public RadGridDP()
    {
    }

    protected override void OnLoad(EventArgs e)
    {
        base.OnLoad(e);
        Button btnExport = new Button();
        btnExport.ID = "Export";
        btnExport.Text = "Export";
        btnExport.Click += new EventHandler(btnExport_Click);
        btnExport.CommandArgument = this.ID;
        this.MasterTableView.Controls.Add(btnExport);
    }

    void btnExport_Click(object sender, EventArgs e)
    {
        Button btnExport = (Button)sender;
        string RadGridId = btnExport.CommandArgument.ToString();
        RadGridDP radGrid = (RadGridDP)this.Parent.Parent.FindControl(RadGridId);

        radGrid.ExportSettings.IgnorePaging = true;
        radGrid.ExportSettings.OpenInNewWindow = true;
        radGrid.ExportSettings.ExportOnlyData = true;

        radGrid.MasterTableView.ExportToExcel();
    }
}

When I do same thing in a UserControl and use that UserControl on any page, it works fine. What’s the difference?

Answer 1

I found out the solution. Whenever RadGrid Loads, it calls various events in this fashion:

1. Page OnLoad
m. RadGrid OnLoad
x. NeedDataSource

and upon click of the button (added in the manner above), events are called in this fashion

1. Page_OnLoad
m. RadGrid OnLoad
n. btnExport_Click
x. NeedDataSource

(as for strange serial numbers, these events may have other events in between, but the order of occurance is correct)
so, entire Grid is rebound with the data, and hence command to exportPdf is flushed. So nothing happens.
Interestingly, there’s no need of adding one extra button, telerik provides its own buttons to do so. which can be customized as well(by implementing ITemplate). This is how am generating Reports now(though not specific to the original question):

    [ToolboxData("<{0}:RadGridDP runat=server></{0}:RadGridDP>")]
    public class RadGridDP : RadGrid
    {
        //custom logic
        public RadGridDP()
        {
            this.ItemCreated += new GridItemEventHandler(RadGrid_ItemCreated);
            this.Load += new EventHandler(RadGridDP_Load);
            this.ItemCommand += new GridCommandEventHandler(RadGrid_ItemCommand);
            this.PdfExporting += new OnGridPdfExportingEventHandler(RadGridDP_PdfExporting);
            this.GridExporting += new OnGridExportingEventHandler(RadGridDP_GridExporting);

            this.ExportSettings.ExportOnlyData = true;
            this.ExportSettings.IgnorePaging = true;
            // this.ExportSettings.OpenInNewWindow = true;

            DoPdfFormatting();
            DoExcelFormatting();

        }
        protected void RadGridDP_PdfExporting(object sender, GridPdfExportingArgs e)
        {
            e.RawHTML = e.RawHTML.Replace("border=\"1\"", "").Replace("style=\"", "style=\" border:0.5px Solid black; ")
                        .Replace("<thead>", String.Format("<thead>{0}", TableHeader)).Replace("</tbody>", String.Format("{0}</tbody>", TableFooter));
        }
        protected void RadGridDP_GridExporting(object sender, GridExportingArgs e)
        {
            e.ExportOutput = e.ExportOutput.Replace("<thead>", String.Format("<thead>{0}", TableHeader))
                             .Replace("</tbody>", String.Format("{0}</tbody>", TableFooter));
        }

  }

so basically i had to handle PdfExporting(for Pdf) and GridExporting(for excel)..
I had to handle Load, ItemCommand and ItemCreated as well. While the former one was required for some conditional logic, later two were required for formatting of the PDF document