Magento 2: Create Invoice Programmatically From Order Observer - php

Question

I'm testing on Magento 2.2.3 and I've created an observer for the event sales_order_save_after which I'm using to automatically create an invoice.
Here is the current error that I'm receiving after placing an order:
Order saving error: Rolled back transaction has not been completed correctly.
And my MyCompany/MyModule/Observer/SalesOrderSaveAfter.php
<?php
namespace MyCompany\MyModule\Observer;
use Magento\Framework\Event\ObserverInterface;
class SalesOrderSaveAfter implements ObserverInterface
{
protected $_invoiceService;
protected $_transactionFactory;
public function __construct(
\Magento\Sales\Model\Service\InvoiceService $invoiceService,
\Magento\Framework\DB\TransactionFactory $transactionFactory
) {
$this->_invoiceService = $invoiceService;
$this->_transactionFactory = $transactionFactory;
}
public function execute(\Magento\Framework\Event\Observer $observer)
{
$order = $observer->getEvent()->getOrder();
try {
if(!$order->canInvoice()) {
return null;
}
if(!$order->getState() == 'new') {
return null;
}
$invoice = $this->_invoiceService->prepareInvoice($order);
$invoice->setRequestedCaptureCase(\Magento\Sales\Model\Order\Invoice::CAPTURE_ONLINE);
$invoice->register();
$transaction = $this->_transactionFactory->create()
->addObject($invoice)
->addObject($invoice->getOrder());
$transaction->save();
} catch (\Exception $e) {
$order->addStatusHistoryComment('Exception message: '.$e->getMessage(), false);
$order->save();
return null;
}
}
}
If I remove the transaction portion of the code, eg:
$transaction = $this->_transactionFactory->create()
->addObject($invoice)
->addObject($invoice->getOrder());
$transaction->save();
then the order will pass through with the products marked as invoiced, but no invoice is actually created or saved to the order.
Any ideas what I could be missing?

Answer 1

https://magento.stackexchange.com/questions/217045/magento-2-how-to-automatically-create-invoice-from-order-observer
The answer to this is that I was using the wrong event. With the event sales_order_save_after the order hasn't been committed to the Database yet.
I changed my event to fire on checkout_submit_all_after and my observer is now working.