1/1) BadMethodCallException Method [validator] does not exist.

using laravel 5.6 and in my controller I have following code,

$input = $request->all();
        $validator = $this->validator($input);

        if ($validator->passes()){
            $booking = $this->create($input)->toArray();
            $booking['link'] = str_random(30);

            DB::table('activations')->insert(['id_user' => $booking['id'], 'token' => $booking['link']]);
            Mail::send('mail.activation', $booking, function($message) use ($booking) {
                $message->to($booking['email']);

                $message->subject('acxian.com - Activation Code');
            });

but when I try submit button following error is occurring,

1/1) BadMethodCallException

Method [validator] does not exist.

how can I fix this?