how to retrieve the model id after successful payment in paypal - laravel - php

Question

i am using express checkout with this package :
https://github.com/srmklive/laravel-paypal
exactly as example repository one change i made is that the price and item info was hard coded but i passed a model to that function called event because i want to sell events . so it looks like below now :
protected function getCheckoutData($recurring = false,$event = null)
{
$data = [];
$order_id = Invoice::all()->count() + 1;
if ($recurring === true) {
$data['items'] = [
[
'name' => 'Monthly Subscription '.config('paypal.invoice_prefix').' #'.$order_id,
'price' => 12222,
'qty' => 1,
],
];
$data['return_url'] = url('/paypal/ec-checkout-success?mode=recurring');
$data['subscription_desc'] = 'Monthly Subscription '.config('paypal.invoice_prefix').' #'.$order_id;
} else {
$data['items'] = [
[
'name' => $event->title,
'price' => $event->price,
'qty' => 1,
'event_id' => $event->id,
]
];
$data['return_url'] = url('/paypal/ec-checkout-success');
}
$data['invoice_id'] = config('paypal.invoice_prefix').'_'.$order_id;
$data['invoice_description'] = $event->title;
$data['cancel_url'] = url('/');
$total = 0;
foreach ($data['items'] as $item) {
$total += $item['price'] * $item['qty'];
}
$data['total'] = $total;
return $data;
}
now on getExpressCheckoutSuccess function after payment it calls the getCheckoutData again but this time there is no model event on that like below :
public function getExpressCheckoutSuccess(Request $request)
{
$recurring = ($request->get('mode') === 'recurring') ? true : false;
$token = $request->get('token');
$PayerID = $request->get('PayerID');
$cart = $this->getCheckoutData($recurring);
// Verify Express Checkout Token
$response = $this->provider->getExpressCheckoutDetails($token);
.
.
.
so my question is that how can pass the paypal my event id and it returns that to me again or do some thing to detect the event
and pass it to getCheckoutData and verify the payment . thanks in advance