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.

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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

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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