public async Task <IActionResult> Buy(int id)
{
string stringEmail = User.Identity.Name;
Cart cart = await _context.GetCart(stringEmail);
CartItems product = new CartItems();
product.InventoryID = id;
product.Quantity = 1;
product.CartID = cart.ID;
await _context.AddCartItem(product);
return(RedirectToAction("Index", "Cart", product));
}