public function changeQuantity(Request $request) { // verify parameters if (!$request->has("itemId") || !$request->has("quantity")) { return new Response("Request must contain itemId and quantity", Response::HTTP_BAD_REQUEST); } $itemId = $request->input("itemId"); $quantity = $request->input("quantity"); // verify valid itemId $cartItem = CartItem::find($itemId); if (is_null($cartItem)) { return new Response("Item id is invalid: " . $itemId, Response::HTTP_NOT_FOUND); } $cartItem->quantity = $quantity; $cartItem->save(); return $this->success(array('itemId' => $itemId, 'quantity' => $quantity)); }