Insert Costum Data

[hrace009]

Hello, I have code like bellow:

public function postPaypalSubmit(Request $request)
    {
        $min = config('pw-config.payment.paypal.minimum');
        $max = config('pw-config.payment.paypal.maximum');
        $request->validate([
            'promo_code' => 'alpha_num',
        ]);
        $promo_code = $request->input('promo_code');

        if ( $request->dollars >= $min && $request->dollars <= $max ) {
            $transaction = $this->gateway->purchase([
                'amount' => number_format($request->dollars, 0, '.', ''),
                'currency' => config('pw-config.payment.paypal.currency'),
                'description' => __('donate.paypal.description', ['amount' => $request->tokens, 'currency' => config('pw-config.currency_name')]),
                'returnUrl' => route('app.donate.paypal.complete'),
                'cancelUrl' => route('app.donate.paypal'),
            ]);
            $response = $transaction->send();

            if ($response->isRedirect()) {
                $response->redirect();
            } else {
                echo $response->getMessage();
            }
        }
        else {
            return redirect()->back()->with('error', __('donate.paypal.transaction_range', ['min' => $min, 'max' => $max ]));
        }
    }

how i can insert $promo_code to $transaction?