private void OnNav(string destination)
        {
            switch (destination)
            {
            case "orderprep":
                CurrentViewModel = _orderPrepViewModel;
                break;

            case "customers":
                CurrentViewModel = _customerListViewModel;
                break;
            }
        }
 private void NavToCustomerList()
 {
     CurrentViewModel = _customerListViewModel;
 }
 private void NavToAddCustomer(Customer customer)
 {
     _addEditViewModel.EditMode = false;
     _addEditViewModel.SetCustomer(customer);
     CurrentViewModel = _addEditViewModel;
 }
 private void NavToEditCustomer(Customer customer)
 {
     _addEditViewModel.EditMode = true;
     _addEditViewModel.SetCustomer(customer);
     CurrentViewModel = _addEditViewModel;
 }
 private void NavToOrder(Guid customerId)
 {
     _orderViewModel.CustomerId = customerId;
     CurrentViewModel           = _orderViewModel;
 }
 private void NavToOrder(Guid customerId)
 {
     _orderViewModel.CustomerId = customerId;
     CurrentViewModel           = _orderViewModel;
     // throw new NotImplementedException();
 }