As another user already mentioned, but without more code I will show you how to do it:

// 将优惠券代码存储在变量中（不需要）
$couponCode = $request->couponCode;

// 通过优惠券代码获取优惠券详情（直接使用first()方法，以便一次性获取模型）
$coupon = Coupon::where('couponCode', $couponCode)->first();

// 在这里，您可以将模型作为JSON响应返回（在视图中使用`$data->couponName`）
response()->json(['data' => $coupon]);

// 或者您可以直接返回优惠券名称
return $couponDetails->couponName;

The error you are getting is because the property you are trying to access does not exist in class Illuminate\Http\JsonResponse.

You have two ways to avoid this problem:

1. Or return:

   return $coupon->couponName;
   

2. Get data from JsonResponse class:

   return $couponDetails->getData()->couponName;