public async Task <IActionResult> Edit(int id, [Bind("Id,FirstName,LastName,Address,Discount")] Customer customer)
        {
            if (id != customer.Id)
            {
                return(NotFound());
            }

            if (ModelState.IsValid)
            {
                try
                {
                    await _customers.EditAsync(customer);

                    return(RedirectToAction(nameof(Index)));
                }
                catch (DbUpdateConcurrencyException)
                {
                    return(BadRequest());
                }
            }
            return(View(customer));
        }