public PhotoViewModel(IRouter router = null, IPhotosService service = null) : base(router)
{
Service = service ?? Locator.Current.GetService <IPhotosService>();
var canLoadData = this.WhenAnyValue(vm => vm.Photo)
.Select(p => p != null);
LoadPhotoData = ReactiveCommand.CreateAsyncTask(canLoadData, async o => await LoadPhotoDataImpl());
photo = OnActivated.Select(p => p.Photo)
.ToProperty(this, vm => vm.Photo);
photoData = LoadPhotoData
.ObserveOn(RxApp.MainThreadScheduler)
.ToProperty(this, vm => vm.PhotoData);
isLoading = LoadPhotoData.IsExecuting
.ObserveOn(RxApp.MainThreadScheduler)
.ToProperty(this, vm => vm.IsLoading);
this.WhenAnyValue(vm => vm.Photo)
.InvokeCommand(this, vm => vm.LoadPhotoData);
}