public ProductItemDetailPage()
        {
            InitializeComponent();

            var item = new ProductItem
            {
                Name     = "Item 1",
                Quantity = 1,
                Location = "no Location"
            };

            viewModel      = new ProductItemDetailViewModel(item);
            BindingContext = viewModel;
        }
        public ProductItemDetailPage(ProductItemDetailViewModel viewModel)
        {
            InitializeComponent();

            BindingContext = this.viewModel = viewModel;
        }