metatag-8.x-1.x-dev/metatag_routes/metatag_routes.module

<?php

/**
 * @file
 * Default hook implementations for the Metatag Routes module.
 */

use Drupal\Core\Routing\RouteMatchInterface;

/**
 * Implements hook_help().
 */
function metatag_routes_help($route_name, RouteMatchInterface $route_match) {
  switch ($route_name) {
    // Main module help for the ok_metatag_custom module.
    case 'help.page.metatag_routes':
      $output = '';
      $output .= '<h3>' . t('About') . '</h3>';
      $output .= '<p>' . t('Enables metatags for custom routes') . '</p>';
      return $output;

    default:
  }
}

/**
 * Implements hook_metatags_alter().
 */
function metatag_routes_metatags_alter(array &$metatags, array $context) {
  // Ignore some system routes that are not appropriate for meta tags.
  if (metatag_is_current_route_supported()) {
    // Look to see if a configuration was assigned for this route.
    /** @var \Drupal\metatag_routes\Helper\MetatagRoutesHelperInterface $metatag_routes_helper */
    $metatag_routes_helper = \Drupal::service('metatag_routes.helper');
    $current_route = $metatag_routes_helper->getCurrentMetatagRouteId();
    if (!empty($current_route)) {
      $defaults = \Drupal::entityTypeManager()
        ->getStorage('metatag_defaults')
        ->load($current_route);
      if (!empty($defaults)) {
        $tags = $defaults->get('tags');

        // Replace the new values and keep on the global values.
        $metatags = array_merge($metatags, $tags);
      }
    }
  }
}