public static List <CashCustomer> GetCustomers(string customerCriteria)
        {
            List <CashCustomer> customers = new List <CashCustomer>();

            using (FreeMarketEntities db = new FreeMarketEntities())
            {
                customers = db.FilterCashCustomers(customerCriteria)
                            .Select(c => new CashCustomer
                {
                    DeliveryAddress = c.DeliveryAddress,
                    Email           = c.Email,
                    Id          = (int)c.Id,
                    Name        = c.Name,
                    PhoneNumber = c.PhoneNumber
                })
                            .ToList();
            }

            if (customers == null)
            {
                return(new List <CashCustomer>());
            }

            return(customers);
        }