public async Task <IActionResult> Edit(int id, [Bind("IdProduct,Sharpness")] Katanas katanas)
        {
            if (id != katanas.IdProduct)
            {
                return(NotFound());
            }

            if (ModelState.IsValid)
            {
                try
                {
                    _context.Update(katanas);
                    await _context.SaveChangesAsync();
                }
                catch (DbUpdateConcurrencyException)
                {
                    if (!KatanasExists(katanas.IdProduct))
                    {
                        return(NotFound());
                    }
                    else
                    {
                        throw;
                    }
                }
                return(RedirectToAction(nameof(Index)));
            }
            ViewData["IdProduct"] = new SelectList(_context.Product, "Id", "Id", katanas.IdProduct);
            return(View(katanas));
        }
        public async Task <IActionResult> Create([Bind("Sharpness")] Katanas katanas, [Bind("Name,IdProductNavigation.Price")] Product product)
        {
            if (ModelState.IsValid)
            {
                katanas.IdProductNavigation = new Product()
                {
                };

                _context.Add(product);
                await _context.SaveChangesAsync();

                katanas.IdProduct = product.Id;
                _context.Add(katanas);
                await _context.SaveChangesAsync();

                return(RedirectToAction(nameof(Index)));
            }
            ViewData["IdProduct"] = new SelectList(_context.Product, "Id", "Id", katanas.IdProduct);
            return(View(katanas));
        }