Magento2 - How to get order id in 'sales_order_invoice_pay' observer?

Question

Here I want to generate a Custom Invoice with Custom data and format right after default invoice generation.

So I have added an observer sales_order_invoice_pay. here I want to get Order Id but I have no idea how can I get order id in this observer.

$order = $observer->getEvent()->getOrder();
$orderId = $order->getId(); //returning NULL

$order = $observer->getEvent()->getOrder();
$incrementId = $order->getIncrementId();//returning NULL

How can I get order id in this observer?

Thanks in Advance.

Answer 1

Try the following way:

/** @var \Magento\Sales\Model\Order\Invoice $invoice */
$invoice = $observer->getEvent()->getInvoice();
$order = $invoice->getOrder();
$incrementId = $order->getIncrementId();