DefaultController.php from https://www.symfony.fi/entry/sharing-state-in-a-symfony-hybrid-app-with-twig-react-etc

DefaultController.php

<?php

    public function indexAction(Request $request )
    {
        $appState = new AppState();
        $em = $this->get('doctrine.orm.default_entity_manager');
        $apartments = $em->getRepository('AppBundle:Apartment')->findByLimit(3);

        $appState->setApartments($apartments);
        $appState->setFetchMore(true);
      
        return $this->render('default/index.html.twig', [
            'appstate' => $appState,
            'appstate_serialized' => $appState->jsonSerialize()
        ]);
    }