public MainViewModel(IPlaneRepository planeRepository) { PlaneRepository = planeRepository; Planes = new ObservableCollection <IPlane>(); RefreshPlanesCommand = new RelayCommand(async() => { var planes = (await PlaneRepository.GetAllPlanesAsync()).ToList(); if (Planes.Any()) { Planes.Clear(); } foreach (var item in planes) { Planes.Add(item); } NotifyPropertyChanged("Planes"); }); }