[Server Side] Footer 핸드링

public static void GridFooterTotal(UltraWebGrid grid, DataTable dataTable, string[] columns, string titleColumn)
{
    grid.DisplayLayout.ColFootersVisibleDefault = ShowMarginInfo.Yes;
    grid.DisplayLayout.StationaryMargins = StationaryMargins.HeaderAndFooter;
    foreach (string columnName in columns)
    {               
        UltraGridColumn column = grid.Columns.FromKey(columnName.Trim());
        column.Footer.Style.HorizontalAlign = HorizontalAlign.Right;
        column.Footer.Style.Padding.Right = 2;
        column.Footer.Caption = dataTable.AsEnumerable().Sum(r => NullCheck(r[columnName.Trim()])).ToString("###,###,###,###.######");
    }

    if (string.IsNullOrEmpty(titleColumn))
        grid.Columns[0].Footer.Caption = CM.TotalText;
    else
        grid.Columns.FromKey(titleColumn).Footer.Caption = CM.TotalText;
}