hreflang.module in Hreflang 8

Adds hreflang link elements to the header of each page.

File

hreflang.module

<?php

/**
 * @file
 * Adds hreflang link elements to the header of each page.
 */
use Drupal\Core\Language\LanguageInterface;
use Drupal\Core\Url;

/**
 * Implements hook_module_implements_alter().
 */
function hreflang_module_implements_alter(&$implementations, $hook) {

  // @fixme https://www.drupal.org/project/drupal/issues/1255092
  // Content Translation module normally adds identical hreflang tags, so
  // executing its hook_page_attachments() implementation would be harmless, but
  // if an entity page is configured as the front page, it attaches extraneous
  // hreflang tags using the entity URL.
  if ($hook === 'page_attachments' && isset($implementations['content_translation'])) {
    unset($implementations['content_translation']);
  }
}

/**
 * Implements hook_page_attachments().
 */
function hreflang_page_attachments(array &$page) {

  // No need to add hreflang tags for 404/403 pages.
  if (\Drupal::request()->attributes
    ->has('exception')) {
    return;
  }
  $language_manager = \Drupal::getContainer()
    ->get('language_manager');
  if (!$language_manager
    ->isMultilingual()) {
    return;
  }
  $route = \Drupal::service('path.matcher')
    ->isFrontPage() ? '<front>' : '<current>';
  $links = $language_manager
    ->getLanguageSwitchLinks(LanguageInterface::TYPE_INTERFACE, Url::fromRoute($route));
  if (empty($links->links)) {
    return;
  }
  foreach ($links->links as $langcode => $link) {
    if (!isset($link['query'])) {
      $link['query'] = [];
    }
    $link['query'] += \Drupal::request()->query
      ->all();
    if (isset($link['url'])) {
      $link['url']
        ->setOptions($link);
      $link['url']
        ->setAbsolute();
      $page['#attached']['html_head_link'][] = [
        [
          'rel' => 'alternate',
          'hreflang' => $langcode,
          'href' => $link['url']
            ->toString(),
        ],
        TRUE,
      ];
    }
  }
}

Functions

Name	Description
hreflang_module_implements_alter	Implements hook_module_implements_alter().
hreflang_page_attachments	Implements hook_page_attachments().