public static List<object> Sum_Products_based_on_filter(RaptorDB.Common.IRaptorDB rap, string filter)
        {
            var q = rap.Query<RaptorDBTest1Views.SalesItemRowsView.RowSchema>(filter);

            var res = from x in q.Rows
                      group x by x.Product into g
                      select new SumType //avoid annonymous types
                      {
                          Product = g.Key,
                          TotalPrice = g.Sum(p => p.Price),
                          TotalQTY = g.Sum(p => p.QTY)
                      };

            return res.ToList<object>();
        }