public string CheckOut(int Customerid, int ShippingAddressId, string PaymentMethod) { List <int?> obj = new List <int?>(); using (var entities = new SedapExpressEntities()) { obj = entities.CheckOut(Guid.NewGuid(), Guid.NewGuid(), Customerid, ShippingAddressId, PaymentMethod).ToList <int?>(); } return(JsonConvert.SerializeObject(obj)); }