ContentTypeHeaderMatcher.php

<?php

namespace Drupal\Core\Routing;

use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpKernel\Exception\UnsupportedMediaTypeHttpException;
use Symfony\Component\Routing\RouteCollection;

/**
 * Filters routes based on the HTTP Content-type header.
 */
class ContentTypeHeaderMatcher implements FilterInterface {
    
    /**
     * {@inheritdoc}
     */
    public function filter(RouteCollection $collection, Request $request) {
        // The Content-type header does not make sense on GET or DELETE requests,
        // because they do not carry any content. Nothing to filter in this case.
        // Same for all other safe methods.
        if ($request->isMethodSafe() || $request->isMethod('DELETE')) {
            return $collection;
        }
        $format = $request->getContentTypeFormat();
        foreach ($collection as $name => $route) {
            $supported_formats = array_filter(explode('|', $route->getRequirement('_content_type_format') ?? ''));
            if (empty($supported_formats)) {
                // No restriction on the route, so we move the route to the end of the
                // collection by re-adding it. That way generic routes sink down in the
                // list and exact matching routes stay on top.
                $collection->add($name, $route);
            }
            elseif (!in_array($format, $supported_formats)) {
                $collection->remove($name);
            }
        }
        if (count($collection)) {
            return $collection;
        }
        // We do not throw a
        // \Symfony\Component\Routing\Exception\ResourceNotFoundException here
        // because we don't want to return a 404 status code, but rather a 415.
        if (!$request->headers
            ->get('Content-Type', FALSE)) {
            throw new UnsupportedMediaTypeHttpException('No "Content-Type" request header specified');
        }
        else {
            throw new UnsupportedMediaTypeHttpException('No route found that matches "Content-Type: ' . $request->headers
                ->get('Content-Type') . '"');
        }
    }

}