d8-podcast-ror/src/Controller/PodcastRorController.php

<?php
namespace Drupal\podcast_ror\Controller;

use Drupal\Core\Controller\ControllerBase;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\DependencyInjection\ContainerInterface;
use Drupal\Core\Template\TwigEnvironment;

class PodcastRorController extends ControllerBase {
    protected $state;
    protected $twig;
    public function __construct($state, TwigEnvironment $twig) {
        $this->state = $state;
        $this->twig = $twig;
    }

    public static function create(ContainerInterface $container) {
        return new static(
            $container->get('state'),
            $container->get('twig')
        );
    }

    private function query() {
        //TODO: estrai argomento dall'url
        $arg = array('ror_news', 'redazionali', 'news_trasmissioni');
        $query = \Drupal::entityQuery('node');
        $query
            ->condition('status', '1')
            ->condition('type', $arg, 'IN')
            ->sort('nid', 'DESC')
            ->range(0, 20);
        $nids = $query->execute();
        // TODO: load contenuti_audio referenced entities
        $data = array();
        $nodes_e = \Drupal\node\Entity\Node::loadMultiple($nids);
        $data['nodes'] =  array();
        foreach($nodes_e as $nid => $node) {
            $data['nodes'][$nid] = $node->toArray();
            $data['nodes'][$nid]['summary'] = htmlspecialchars(substr(
                html_entity_decode(strip_tags($data['nodes'][$nid]['body'][0]['value'])),
                0, 3500), ENT_XML1, 'UTF-8');
        }

        $data['audio'] = array();
        $first = true;
        foreach($nodes_e as $nid => $node) {
            $data['audio'][$nid] = array();
            foreach( $node->get('field_contenuti_audio')->referencedEntities() as $ai => $audio)  {
                // print_r(get_class_methods(get_class($audio)));
                $data['audio'][$nid][$ai] = $audio->toArray();
            }
            if($first === true) {
                $first = false;
            }
        }
        return $data;
    }
    public function podcastAll() {
        $template = $this->twig->loadTemplate(drupal_get_path('module', 'podcast_ror') . '/templates/podcast.html.twig');
        $tmpl_data = [ 'ror' => array('podcast' => $this->query(),
            'url' => \Drupal::service('path.current')->getPath(),
        )];
	$variables['ror']['url'] = 
        $xml = $template->render($tmpl_data);
        $resp = new Response($xml, 200, array(
            'Content-Type' => 'application/rss+xml'));
        return $resp;
    }
}