public void ConfirmProduct() { Product product = new Product() { Amount = Amount, NetPrice = NetPrice * Amount, Name = ProductName, GrossPrice = NetPrice * Amount * (decimal)1.23 }; List <(string, bool)> validators = DataValidation.CheckProductFields(product); foreach (var validator in validators) { if (!validator.Item2) { MessageBox.Show(validator.Item1, "Warning", MessageBoxButton.OK, MessageBoxImage.Warning); break; } } if (validators.TrueForAll(x => x.Item2)) { products.Items.Add(product); } }