private void FillWithDummyData()
        {
            FullPrice = "$100.50";
            TotalDiscount = "$10.50";
            TotalPrice = "$90.00";

            ShoppingCartItemViewModels = new ObservableCollection<ShoppingCartItemViewModel>()
                {
                    new ShoppingCartItemViewModel(new ShoppingCartItem()
                        {
                            Id = Guid.NewGuid().ToString(),
                            Product = new Product() {  Title = "Product 1",  Description = "Description of Product 1", ListPrice = 25.10, ProductNumber = "1", ImageUri = new Uri("ms-appx:///Assets/StoreLogo.png")},
                            Quantity = 1,
                            Currency = "USD"
                        }),
                   new ShoppingCartItemViewModel(new ShoppingCartItem()
                        {
                            Id = Guid.NewGuid().ToString(),
                            Product = new Product() {  Title = "Product 2",  Description = "Description of Product 2", ListPrice = 25.10, ProductNumber = "2", ImageUri = new Uri("ms-appx:///Assets/StoreLogo.png")},
                            Quantity = 20,
                            Currency = "USD"
                        }), 
                   new ShoppingCartItemViewModel(new ShoppingCartItem()
                        {
                            Id = Guid.NewGuid().ToString(),
                            Product = new Product() {  Title = "Product 3",  Description = "Description of Product 3", ListPrice = 25.10, ProductNumber = "3", ImageUri = new Uri("ms-appx:///Assets/StoreLogo.png")},
                            Quantity = 30,
                            Currency = "USD"
                        }), 
                   new ShoppingCartItemViewModel(new ShoppingCartItem()
                        {
                            Id = Guid.NewGuid().ToString(),
                            Product = new Product() {  Title = "Product 4",  Description = "Description of Product 4", ListPrice = 25.10, ProductNumber = "4", ImageUri = new Uri("ms-appx:///Assets/StoreLogo.png")},
                            Quantity = 14,
                            Currency = "USD"
                        }), 
                   new ShoppingCartItemViewModel(new ShoppingCartItem()
                        {
                            Id = Guid.NewGuid().ToString(),
                            Product = new Product() {  Title = "Product 5",  Description = "Description of Product 5", ListPrice = 25.10, ProductNumber = "5", ImageUri = new Uri("ms-appx:///Assets/StoreLogo.png")},
                            Quantity = 25,
                            Currency = "USD"
                        }), 
                };

            SelectedItem = ShoppingCartItemViewModels[0];
        }
 private async Task Remove(ShoppingCartItemViewModel item)
 {
     if (item != null)
     {
         await _shoppingCartRepository.RemoveShoppingCartItemAsync(item.Id);
     }
     ShoppingCartItemViewModels.Remove(item);
     CheckoutCommand.RaiseCanExecuteChanged();
     OnPropertyChanged("FullPrice");
     OnPropertyChanged("TotalDiscount");
     OnPropertyChanged("TotalPrice");
 }
        public async void UpdateShoppingCartAsync(object notUsed)
        {
            _shoppingCart = await _shoppingCartRepository.GetShoppingCartAsync();

            if (_shoppingCart != null && _shoppingCart.ShoppingCartItems != null)
            {
                ShoppingCartItemViewModels = new ObservableCollection<ShoppingCartItemViewModel>();
                foreach (var item in _shoppingCart.ShoppingCartItems)
                {
                    var shoppingCartItemViewModel = new ShoppingCartItemViewModel(item);
                    shoppingCartItemViewModel.PropertyChanged += shoppingCartItemViewModel_PropertyChanged;
                    ShoppingCartItemViewModels.Add(shoppingCartItemViewModel);
                }
                CheckoutCommand.RaiseCanExecuteChanged();
                OnPropertyChanged("FullPrice");
                OnPropertyChanged("TotalDiscount");
                OnPropertyChanged("TotalPrice");
            }
        }