/// <summary>
/// Constructor for the Main view model.
/// </summary>
/// <param name="serviceLocator"></param>
public MainViewModel(IDependencyService serviceLocator)
{
this.serviceLocator = serviceLocator;
diaryService = serviceLocator.Get <IDiaryService>();
AddEntry = new AsyncDelegateCommand(OnAddEntryAsync);
SaveEntry = new AsyncDelegateCommand(OnSaveEntryAsync, () => SelectedEntry == null ? false : SelectedEntry.CanSave);
DeleteEntry = new AsyncDelegateCommand(OnDeleteEntryAsync, de => de != null || (SelectedEntry != null && !SelectedEntry.IsNew));
Refresh = new AsyncDelegateCommand(() => deEntries.RefreshAsync());
SelectEntry = new AsyncDelegateCommand(() => serviceLocator.Get <INavigationService>().NavigateAsync(AppPage.Detail));
// Lab3: Add logout command
Logout = new AsyncDelegateCommand(OnClearAuthAsync);
deEntries = new RefreshingCollection <DiaryEntryViewModel>(LoadDiaryEntriesAsync)
{
BeforeRefresh = c =>
{
IsBusy = true;
return(SelectedEntry);
},
AfterRefresh = (c, o) =>
{
IsBusy = false;
SelectedEntry = (DiaryEntryViewModel)o;
},
RefreshFailed = (c, ex) =>
{
IsBusy = false;
return(serviceLocator.Get <IMessageVisualizerService>().ShowMessage(
"Are you connected?", ex.Flatten(), "OK"));
}
};
// Set the 1st entry as active.
deEntries.RefreshAsync()
.ContinueWith(tr =>
{
SelectedEntry = deEntries.FirstOrDefault();
},
CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, TaskScheduler.FromCurrentSynchronizationContext());
}
/// <summary>
/// Constructor
/// </summary>
/// <param name="surveyService">Service to retrieve data from</param>
/// <param name="dependencyService">Service Locator</param>
public MainViewModel(ISurveyQuestionService surveyService, IDependencyService dependencyService)
{
this.surveyService = surveyService;
this.dependencyService = dependencyService;
// Setup our collection of questions. This is an async collection populated by our
// survey service. The single constructor parameter is an async function to load the data.
questions = new RefreshingCollection <SurveyQuestion>(surveyService.GetQuestionsAsync)
{
// What to do if the refresh fails..
RefreshFailed = async(s, ex) =>
{
IsLoadingData = false;
await Task.Delay(1000); // get out of the binding.
await dependencyService.Get <IMessageVisualizerService>()
.ShowMessage("Error", "Failed to get questions: " + ex.Message, "OK");
},
// Called before a refresh occurs to save off the current selection.
BeforeRefresh = s =>
{
IsLoadingData = true;
return(SelectedQuestion);
},
// Called after a refresh completes successfully; restores the selection.
AfterRefresh = (s, sq) =>
{
IsLoadingData = false;
if (sq == null)
{
sq = questions.FirstOrDefault();
}
if (sq != null)
{
var newSelection = questions.SingleOrDefault(q => q.Id == ((SurveyQuestion)sq).Id);
SelectedQuestion = newSelection;
}
}
};
// Setup the collection of answers; this is refreshed each time the
// selected question changes.
answers = new RefreshingCollection <AnswerViewModel>(async() =>
{
IsLoadingData = true;
try
{
var id = SelectedQuestion.Id;
string [] choices = SelectedQuestion.Answers.Split('|');
if (HasName)
{
response = await surveyService.GetResponseForSurveyAsync(id, Name);
}
else
{
response = null;
}
int answerIndex = response == null ? -1 : response.ResponseIndex;
return(Enumerable.Range(0, choices.Length)
.Select(i => new AnswerViewModel(choices [i], i)
{
IsSelected = answerIndex == i
}));
}
catch (Exception ex)
{
await dependencyService.Get <IMessageVisualizerService>()
.ShowMessage("Error", "Failed to get answers/responses: " + ex.Message, "OK");
return(null);
}
finally
{
IsLoadingData = false;
}
});
}
