ws_orderreference/controllers/front/ajax.php

<?php

use Module\WsOrderreference\Entity\OrderReference;
use Module\WsOrderreference\Repository\OrderReferenceRepository;

if (file_exists(__DIR__ . '../../vendor/autoload.php')) {
    require_once __DIR__ . '../../vendor/autoload.php';
}

class ws_orderreferenceAjaxModuleFrontController extends ModuleFrontController
{
    public function initContent()
    {
        $orderReference = Tools::getValue('order_reference_input');
        $idCart = $this->context->cart->id;
        
        if (!$idCart) {
            $this->ajaxRender(json_encode([
                'success' => false,
                'message' => $this->module->l('No cart found.', 'ajax')
            ]));
            return;
        }
        
        if (!preg_match('/^[a-zA-Z0-9_\- ]+$/', $orderReference)) {
            $this->ajaxRender(json_encode([
                'success' => false, 
                'message' => $this->module->l('Please enter a valid order reference. Characters allowed: a-z, 0-9, -, _ and space', 'ajax')
            ]));
            return;
        }
        
        try {
            /** @var \Doctrine\ORM\EntityManagerInterface $entityManager */
            $entityManager = $this->get('doctrine.orm.default_entity_manager');
            
            /** @var OrderReferenceRepository $repository */
            $repository = $entityManager->getRepository(OrderReference::class);
        
            $orderRef = $repository->findByCartId($idCart);
            
            if (!$orderRef) {
                $orderRef = new OrderReference();
                $orderRef->setIdCart($idCart);
            }
            
            $orderRef->setOrderReference($orderReference);

            $entityManager->persist($orderRef);
            $entityManager->flush();
            
            $this->ajaxRender(json_encode([
                'success' => true,
                'message' => $this->module->l('Order reference received!', 'ajax')
            ]));
        } catch (Exception $e) {
            $this->ajaxRender(json_encode([
                'success' => false,
                'message' => $this->module->l('Could not save order reference.', 'ajax') 
            ]));
        }
    }
}