public async void AddToCart(object o, System.EventArgs e)
{
if (string.IsNullOrEmpty(this.quantityEntry.Text))
{
await DisplayAlert("Add to cart", "Please enter quantity", "Ok");
}
else
{
await DisplayAlert("Add to cart", "Success", "Ok");
this.quantity = Int32.Parse(this.quantityEntry.Text);
CartViewModel cvm = new CartViewModel();
await cvm.CreateCart(new Model.Cart {
ProductId = this.product.ProductId, Quantity = quantity, UserId = userId
});
}
}