public MainWindow()
        {
            InitializeComponent();
            Window = this;
            loginControl login = new loginControl();

            ContentGrid.Children.Add(login);
        }
        private void Register(object sender, RoutedEventArgs e)
        {
            if (!CheckRequired())
            {
                MainWindow.Window.AddMessageBox("Required fields are empty", "Missing Data", MainWindow.Type.Error);
                return;
            }
            KundeRepository kundeRepository = new KundeRepository();


            string usersalututation = Enum.GetName(typeof(KundeRepository.Anrede), (KundeRepository.Anrede)(SalutationComboBox.SelectedIndex));

            Enum.TryParse <KundeRepository.Anrede>(usersalututation, out var mySalutation);


            kundeRepository.addKunde(mySalutation, FirstnameTxtbox_.Text, SecondnameTxtbox.Text, LastnameTxtbox_.Text, SteetNrTxtbox_.Text, Convert.ToInt16(ZIPTxtbox_.Text), PlaceTxtbox_.Text, PhoneTxtbox.Text, MobileTxtbox.Text, EmailTxtbox_.Text, (DateTime)BirthdateDtPck.SelectedDate, PassNrTxtbox.Text, NationalityCombobox_.SelectedValue.ToString(), usnTxtBox_.Text, passwordBox.Password);
            MainWindow.Window.AddMessageBox("You were successfully registered", "Success");
            MainWindow.Window.ContentGrid.Children.Remove(this);
            loginControl login = new loginControl();

            MainWindow.Window.ContentGrid.Children.Add(login);
        }