private async void OnSelectAnswer(object sender, EventArgs e) { var selectedQuestion = GetSelectedQuestion(); Debug.Assert(selectedQuestion != null); Debug.Assert(string.IsNullOrEmpty(userName) == false); int pos = answerGroup.Children.IndexOf((Button)sender); if (response == null) { response = new SurveyResponse { Name = userName, ResponseIndex = pos, SurveyQuestionId = selectedQuestion.Id }; } else { Debug.Assert(response.Name == userName); Debug.Assert(response.SurveyQuestionId == selectedQuestion.Id); response.ResponseIndex = pos; } await service.AddOrUpdateSurveyResponseAsync(response); SetSelectedAnswer(); }