@UiHandler("save")
  void saveCustomer(ClickEvent event) {
    if (customer == null) {
      customer = new CustomerModel();
    }

    // Update the fields
    customer.setFirstname(firstname.getText());
    customer.setLastname(lastname.getText());
    customer.setBirthdate(birthdate.getValue());

    // Call the presenter
    presenter.saveCustomer(customer);
  }