public CarViewModel() { Cars = new ObservableCollection <Car> { Car.Create("Audi", new ObservableCollection <CarModel> { CarModel.Create("A1"), CarModel.Create("A2"), CarModel.Create("A3"), CarModel.Create("A4"), CarModel.Create("A5") }), Car.Create("Mercedes", new ObservableCollection <CarModel> { CarModel.Create("A-Class"), CarModel.Create("B-Class"), CarModel.Create("C-Class"), CarModel.Create("E-Class"), CarModel.Create("S-Class") }), Car.Create("BMW", new ObservableCollection <CarModel> { CarModel.Create("1-Serie"), CarModel.Create("2-Serie"), CarModel.Create("3-Serie"), CarModel.Create("4-Serie"), CarModel.Create("5-Serie") }), Car.Create("Volkswagen", new ObservableCollection <CarModel> { CarModel.Create("Golf"), CarModel.Create("Passat"), CarModel.Create("Arteon"), CarModel.Create("T-Cross"), CarModel.Create("Up!") }), Car.Create("Volvo", new ObservableCollection <CarModel> { CarModel.Create("V60"), CarModel.Create("V70"), CarModel.Create("XC60"), CarModel.Create("XC90"), CarModel.Create("S90") }), }; DeleteModelCommand = new DelegateCommand(DeleteModelExecuted, DeleteModelCanExecute); DeleteCarCommand = new DelegateCommand(DeleteCarExecuted, DeleteCarCanExecute); AddCarCommand = new DelegateCommand(AddCarExecuted, AddCarCanExecute); AddModelCommand = new DelegateCommand(AddModelExecuted, AddModelCanExecute); }