public IEnumerable<Waste> GetWasteForSeller(Seller seller, DateTime dateFrom, DateTime dateTo)
 {
     dateTo = dateTo.AddDays(1);
     using (var context = new EugenieEntities(connectionStringAsString))
     {
         var wastes =
             context.Wastes.Where(
                 x => x.SellerID == seller.ID && x.Date.CompareTo(dateFrom) >= 0 && x.Date.CompareTo(dateTo) <= 0)
                 .ToList();
         return wastes;
     }
 }
        public void AddWasteToSellerAsync(Seller originalSeller, Waste waste)
        {
            using (var worker = new BackgroundWorker())
            {
                worker.DoWork += (object sender, DoWorkEventArgs e) =>
                {
                    using (var context = new EugenieEntities(connectionStringAsString))
                    {
                        var seller = context.Sellers.Find(originalSeller.ID);
                        seller.Wastes.Add(waste);
                        context.SaveChanges();
                    }
                };

                worker.RunWorkerAsync();
            }
        }