TestController.php

<?php

namespace Drupal\content_negotiation_test\Controller;

use Symfony\Component\HttpFoundation\JsonResponse;
use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;

/**
 * Test controller for content negotiation tests.
 */
class TestController {
    
    /**
     * Returns a json response.
     *
     * @return \Symfony\Component\HttpFoundation\JsonResponse
     */
    public function simple() {
        return new JsonResponse([
            'some' => 'data',
        ]);
    }
    
    /**
     * Returns a simple render array.
     *
     * @return array
     */
    public function html() {
        return [
            '#markup' => 'here',
        ];
    }
    
    /**
     * Returns different responses depending on the request format.
     *
     * @param \Symfony\Component\HttpFoundation\Request $request
     *   The request
     *
     * @return \Symfony\Component\HttpFoundation\Response
     *   The response.
     */
    public function format(Request $request) {
        switch ($request->getRequestFormat()) {
            case 'json':
                return new JsonResponse([
                    'some' => 'data',
                ]);
            case 'xml':
                return new Response('<xml></xml>', Response::HTTP_OK, [
                    'Content-Type' => 'application/xml',
                ]);
            default:
                return new Response($request->getRequestFormat());
        }
    }
    
    /**
     * Returns a render array depending on some passed in value.
     *
     * @param string $plugin_id
     *   The plugin ID.
     *
     * @return array
     *   The render array
     */
    public function variable($plugin_id) {
        return [
            '#markup' => $plugin_id,
        ];
    }

}