public IActionResult Buy(int shoppingCartId, Item item)
 {
     // This checks if the model's state matches what the database has.
     if (ModelState.IsValid)
     {
         // the itemId is set to zero by default
         item.Id = 0;
         // The buy item method is called from the repository.
         _repo.BuyItem(shoppingCartId, item);
         // It returns back to the home index
         return(RedirectToAction("Index", "Home"));
     }
     // The buy item page is displayed
     return(View(item));
 }