private void UiAddBoxBtn_Click(object sender, RoutedEventArgs e) { if (string.IsNullOrEmpty(uiBoxName.Text)) { MessageBox.Show("Box name is required"); return; } if (_currentBoxes.FirstOrDefault(box => box.Title == uiBoxName.Text) != null) { MessageBox.Show("Box with this name already exists"); return; } _dbProvider.AddBox(uiBoxName.Text, appContext.CurrentUser.Id); Refresh(); }