private void NewButton_Click(object sender, RoutedEventArgs e) { if (!IsDataInCorrectForm()) { return; } var result = MessageBox.Show("Tou are requesting to add new supplier", "Confirmation", MessageBoxButton.YesNo, MessageBoxImage.Question); if (result == MessageBoxResult.No) { return; } IdTextBox.Text = Supplier.GetNextSupplierId().ToString(); CreateNewItemFromData(); if (!Supplier.AddNewSupplier(_selectedSupplier)) { ClearPropertyBoxes(); MessageBox.Show("Dupplicate entry", "Error", MessageBoxButton.OK, MessageBoxImage.Error); } else { MessageBox.Show("Successfully added", "Information", MessageBoxButton.OK, MessageBoxImage.Information); RefreshDataGrid(); listBox.ItemsSource = null; } }