How to set global variable laravel - laravel

Question

I tried to make a global variable in laravel, in my code when the json return response, the data appears, but the other method is why it is null,
there is my code
class VendorController extends Controller
{
private $vendor_id;
public function index(){
if($cek =='available')
{
$this->vendor_id = DB::getPdo()->lastInsertId();
return response()->json([
'status' => 'success',
'vendor_id' => $this->vendor_id
]);
}
}
public function cek(){
dd($this->vendor_id)
}
}
when in function cek $this->vendor_id result is null, but in index function return->response()->json() there data is 13

Answer 1

Because that's different controller's instance. So you set the vendor_id in your index action, it will not display in show action,
Try to use session or redis to store the vendor_id:
Session:
public function index(){
...
$vendor_id = DB::getPdo()->lastInsertId();
$request->session()->put('vendor_id', $vendor_id);
...
}
public function show () {
$vendor_id = $request->session()->get('vendor_id'); // get your vendor_id
...
}
Redis:
PS: You need to install redis in your server.
use Illuminate\Support\Facades\Redis;
public function index(){
...
$vendor_id = DB::getPdo()->lastInsertId();
Redis::set('vendor_id', $vendor_id);
...
}
public function show () {
...
$vendor_id = Redis::get('vendor_id');
}

Answer 2

This is right way:-> Please Follow this
class VendorController extends Controller
{
private $vendor_id;
public function __construct(){
$this->vendor_id=DB::getPdo()->lastInsertId();
}
public function show(){
dd($this->vendor_id);
}
}