private async Task GatherResults(ISurveyQuestionService service, SurveyQuestion question)
{
string[] answers = question.Answers.Split('|');
var responses = await service.GetResponsesForSurveyAsync(question.Id);
foreach (var r in responses)
{
Results.Add(new OneResultViewModel {
Name = r.Name,
Answer = answers [r.ResponseIndex]
});
}
}
private async void OnShowResults(object sender, EventArgs e)
{
var selectedQuestion = GetSelectedQuestion();
if (selectedQuestion == null)
{
return;
}
string[] answers = selectedQuestion.Answers.Split('|');
// Populate the results asynchronously -- do not await this call or
// it will become synchronous with respect to the push to the next screen.
var results = new ObservableCollection <Tuple <string, string> >();
var fillDataTask = service.GetResponsesForSurveyAsync(selectedQuestion.Id);
var t1 = fillDataTask.ContinueWith(tr => {
foreach (var r in tr.Result)
{
if (r.ResponseIndex >= 0 && r.ResponseIndex < answers.Length)
{
results.Add(Tuple.Create(r.Name, answers[r.ResponseIndex]));
}
}
},
CancellationToken.None,
TaskContinuationOptions.OnlyOnRanToCompletion,
TaskScheduler.FromCurrentSynchronizationContext());
// If our async fill fails, then show an error.
var t2 = fillDataTask.ContinueWith(async tr => {
await this.DisplayAlert("Error", "Failed to download response: " + tr.Exception.Message, "OK");
}, TaskContinuationOptions.OnlyOnFaulted);
// And display the results page.
await Navigation.PushAsync(new ResultsPage { BindingContext = new { Question = selectedQuestion.Question, Answers = results } });
}