function NodeViewController::view

Overrides EntityViewController::view

File

core/modules/node/src/Controller/NodeViewController.php, line 70

Class

NodeViewController

Defines a controller to render a single node.

Namespace

Code

public function view(EntityInterface $node, $view_mode = 'full', $langcode = NULL) {
    $build = parent::view($node, $view_mode, $langcode);
    foreach ($node->uriRelationships() as $rel) {
        $url = $node->toUrl($rel)
            ->setAbsolute(TRUE);
        // Add link relationships if the user is authenticated or if the anonymous
        // user has access. Access checking must be done for anonymous users to
        // avoid traffic to inaccessible pages from web crawlers. For
        // authenticated users, showing the links in HTML head does not impact
        // user experience or security, since the routes are access checked when
        // visited and only visible via view source. This prevents doing
        // potentially expensive and hard to cache access checks on every request.
        // This means that the page will vary by user.permissions. We also rely on
        // the access checking fallback to ensure the correct cacheability
        // metadata if we have to check access.
        if ($this->currentUser
            ->isAuthenticated() || $url->access($this->currentUser)) {
            // Set the node path as the canonical URL to prevent duplicate content.
            $build['#attached']['html_head_link'][] = [
                [
                    'rel' => $rel,
                    'href' => $url->toString(),
                ],
                TRUE,
            ];
        }
        if ($rel == 'canonical') {
            // Set the non-aliased canonical path as a default shortlink.
            $build['#attached']['html_head_link'][] = [
                [
                    'rel' => 'shortlink',
                    'href' => $url->setOption('alias', TRUE)
                        ->toString(),
                ],
                TRUE,
            ];
        }
    }
    // Since this generates absolute URLs, it can only be cached "per site".
    $build['#cache']['contexts'][] = 'url.site';
    // Given this varies by $this->currentUser->isAuthenticated(), add a cache
    // context based on the anonymous role.
    $build['#cache']['contexts'][] = 'user.roles:anonymous';
    return $build;
}