private void ClearSchedule()
 {
     using (RessourceScheduleManager manager = new RessourceScheduleManager())
     {
         manager.ClearScheduleForPeriod(ScheduleFromDate, ScheduleUntilDate);
     }
 }
        private void ExportSchedule()
        {
            using (ExcelPackage package = new ExcelPackage())
            {
                var worksheet = package.Workbook.Worksheets.Add("Einsatzplan");

                using (RessourceScheduleManager manager = new RessourceScheduleManager())
                {
                    manager.ExportScheduleForPeriod(worksheet, ScheduleFromDate, ScheduleUntilDate);
                }

                SaveFileDialog dialog = new SaveFileDialog();
                dialog.AddExtension = true;
                dialog.DefaultExt   = "*.xlsx";
                dialog.Filter       = string.Format("Excel (*{0})|*{0}", "*.xlsx");
                var result = dialog.ShowDialog();
                if (result ?? false)
                {
                    package.SaveAs(new FileInfo(dialog.FileName));
                }
            }
        }