DevExpress Xtra Report: How to display a label in group footer when the detail band does not have any data?

If a have a lable called: lblWarning. I'd like to display 开发者_StackOverflow中文版it (Visible = True) when the detail band does not have any records. The label is in the group footer.

This event is attached to the report itself (in my example, it's named XtraReport1). GetCurrentRow() is a method on XtraReportBase that returns the current data from the primary report binding source. If data does not exist, it returns null.

private void XtraReport1_BeforePrint(object sender, PrintEventArgs e)
{
    bool noDataFound = GetCurrentRow() == null;

    lblWarning.Visible = noDataFound;
}

The same handler in VB:

Private Sub XtraReport1_BeforePrint(ByVal sender As System.Object, ByVal e As PrintEventArgs) Handles MyBase.BeforePrint
    Dim noDataFound As Boolean = GetCurrentRow() Is Nothing

    lblWarning.Visible = noDataFound
End Sub

Not in front of my dev machine at the moment however something like this may work

Dim HadRecords As Boolean = False

Private Sub GroupFooter1_BeforePrint(ByVal sender As Object, ByVal e As System.Drawing.Printing.PrintEventArgs) Handles GroupFooter1.BeforePrint
    If HadRecords = False Then
        lblWarning.visible = True
    Else
        lblWarning.visible = False
        HadRecords = False ' reset the flag '
    End If
End Sub

Private Sub Detail_BeforePrint(ByVal sender As Object, ByVal e As System.Drawing.Printing.PrintEventArgs) Handles Detail.BeforePrint
    HadRecords = True ' set the flag '
End Sub