/// <summary>
/// Saves or Adds a DiaryEntry to the DB.
/// </summary>
/// <returns></returns>
private async Task OnSaveEntryAsync()
{
if (SelectedEntry != null && SelectedEntry.CanSave)
{
if (SelectedEntry.IsNew)
{
var selEntry = SelectedEntry.Model;
await diaryService.AddEntryAsync(selEntry);
await deEntries.RefreshAsync();
SelectedEntry = Entries.FirstOrDefault(e => e.Model.Id == selEntry.Id);
}
else
{
await diaryService.UpdateEntryAsync(SelectedEntry.Model);
}
// Saved/updated - turn off save flag.
if (SelectedEntry != null)
{
SelectedEntry.CanSave = false;
}
}
}
/// <summary>
/// Creates a new DiaryEntry in the UI. Note that this does _not_ save
/// the entry to the DB; that is done by the SaveCommand.
/// </summary>
/// <returns></returns>
private async Task OnAddEntryAsync()
{
DiaryEntryViewModel vm = new DiaryEntryViewModel();
SelectedEntry = vm;
await serviceLocator.Get <INavigationService>().NavigateAsync(AppPage.Detail);
}
// Lab3: Add logout implementation
/// <summary>
/// This method is called to logoff and force a re-authentication.
/// </summary>
/// <returns></returns>
private async Task OnClearAuthAsync()
{
await diaryService.LogoffAsync();
await deEntries.RefreshAsync();
SelectedEntry = deEntries.FirstOrDefault();
}
/// <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>
/// Deletes a DiaryEntry from the database and removes it from our collection.
/// </summary>
/// <param name="de"></param>
/// <returns></returns>
private async Task OnDeleteEntryAsync(object input)
{
// Can be invoked either through ActionBar button or ContextAction.
var de = input as DiaryEntryViewModel;
if (de == null)
{
de = SelectedEntry;
}
if (de != null)
{
await diaryService.DeleteEntryAsync(SelectedEntry.Model);
Entries.Remove(de);
if (SelectedEntry == de)
{
SelectedEntry = Entries.FirstOrDefault();
}
}
}
