How to Express a Block as a Twig Variable (Drupal 8)

It’s not uncommon to have pages on a Drupal site with very specific layouts, requiring custom twig templating. But what do you do if you need to place a block with automated content between content-managed fields in the same region? How do you place that block within your twig template?

In this post I’m going to show you how to create a Twig variable for both a Views block and a custom block to place in your theme’s twig templates.

Views Block Twig Variable

In order to create a Twig variable of a Views block, we’ll need a preprocess function like this:

function mymodule_preprocess_node(&$variables) {
  $variables['VARIABLE_NAME'] = views_embed_view('VIEW_MACHINE_NAME', 'BLOCK_MACHINE NAME');
}

You can find the machine name of the view on the views admin page:

The machine name of the block you want to place can be found in the Advanced section of the view’s edit page:

Now you will be able to place your block your node twig template (or other template if you place it in a different preprocess function) using the variable you’ve declared:

{{ VARIABLE_NAME }}

Custom Block Twig Variable

This method involves creating a pseudo field that can be placed as a twig variable. The example below shows the steps to create a pseudo field for a taxonomy term, required due to the dynamic nature of the content.

/**
 * @file
 * Functions to create a pseudo field for a taxonomy page.
 */

/**
 * Implements hook_page_attachments().
 */
function mymodule_page_attachments(array &$attachments) {
  $attachments['#attached']['library'][] = 'module_name/moduleName';
  $attachments['#attached']['drupalSettings']['module_name'] = '';
}
/**
 * Implements hook_entity_extra_field_info().
 */
function mymodule_entity_extra_field_info() {
  $fields = [];
  $fields['taxonomy_term']['TERM_MACHINE_NAME']['display']['FIELD_VARIABLE_NAME'] = [
    'label' => t('Label Name'),
    'weight' => 100,
    'visible' => TRUE,
  ];
  return $fields;
}
/**
 * Implements hook_ENTIIY_TYPE_view().
 */
function mymodule_taxonomy_term_view(array &$build, EntityInterface $entity, EntityViewDisplayInterface $display) {
  $markup = '';
  if ($display->getComponent('FIELD_VARIABLE_NAME')) {
    $build['FIELD_VARIABLE_NAME'] = [
      '#markup' => $markup,
    ];
    return $build;
  }
}

With this in place, we are able add the custom block to our twig template using the conventional field convention:

{{ content.FIELD_VARIABLE_NAME }}