Magento 2 place order in custom controller (difference between placeOrder and submit)

Question

In How to create order programmatically in Magento 2? it shows two methods on how to place a quote as an order. The first method uses

$order = $this->quoteManagement->submit($quote);

via \Magento\Quote\Model\QuoteManagement. This returns an \Magento\Sales\Model\Order object.

The second method is using

$cart = $this->cartRepositoryInterface->get($cart->getId());
$order_id = $this->cartManagementInterface->placeOrder($cart->getId());

This method uses both the \Magento\Quote\Api\CartRepositoryInterface $cartRepositoryInterface and the \Magento\Quote\Api\CartManagementInterface $cartManagementInterface.

Another approach I found is basically the first one, but using \Magento\Quote\Api\CartManagementInterface instead...

What are the differences between those approaches?

Answer 1

Calling $this->cartManagementInterface->placeOrder($cart->getId()) will still use $this->quoteManagement->submit($quote); to create the order, only difference is that after the order is successfully created, the checkout session is updated with the quote and order details:

 $this->checkoutSession->setLastQuoteId($quote->getId());
 $this->checkoutSession->setLastSuccessQuoteId($quote->getId());
 $this->checkoutSession->setLastOrderId($order->getId());
 $this->checkoutSession->setLastRealOrderId($order->getIncrementId());
 $this->checkoutSession->setLastOrderStatus($order->getStatus());

This is useful if you're placing your order from frontend since the success page is using the checkoutSession info for displaying.