Forced rendered node view results in empty node links

Question

In order to send html email using drupal/swiftmailer I load and view a node.

Then I pass it to the rendere. In the email sent, generated node__links are empty. As node_links uses #LazyBuilder, Im then not sure to use the correct way.

hook_mail

function mymodule_mail($key, &$message, $params) {
   switch ($key) {
       case 'mail_node':
           $message['from'] = \Drupal::config('system.site')->get('mail');
           $message['headers']['Content-Type'] = 'text/html; charset=UTF-8; format=flowed; delsp=yes';
           $message['subject'] = t('Mail subject');

           $node = Node::load($params['nid']);
           $view_builder = \Drupal::entityTypeManager()->getViewBuilder('node');


           $body_data = [
               '#theme' => 'mymodule_mail_node',
               '#content' => $view_builder->view( $node ),
           ];

           $message['body'][] = \Drupal::service('renderer')->render($body_data);
       break;
       }
 }

mymodule--mail-node.html.twig

 {# simply render the whole body #}
 {{ body }}

output results in mail

<!-- THEME DEBUG -->
<!-- THEME HOOK: 'links__node' -->
<!-- FILE NAME SUGGESTIONS:
    x links--node.html.twig
    * links.html.twig
-->
<!-- BEGIN OUTPUT from 'core/themes/classy/templates/content/links--node.html.twig' -->

<!-- END OUTPUT from 'core/themes/classy/templates/content/links--node.html.twig' -->

When I render the same content into an html page, node__links are correctly filled.

Any recommandation would be appreciate. Thanks

Answer 1

Use renderPlain():

$message['body'][] = \Drupal::service('renderer')->renderPlain($body_data);

From the documentation:

Renders final HTML in situations where no assets are needed.

Calls ::render() in such a way that placeholders are replaced.

Useful for instance when rendering the values of tokens or emails, which need a render array being turned into a string, but do not need any of the bubbleable metadata (the attached assets and cache tags).

Source: Renderer::renderPlain

---

"When I render the same content into an html page, node__links are correctly filled."

render() in a page works, because the page has a render context for the metadata to bubble up, so that the placeholders can be replaced later.