How do I get the referring entity of a referenced node in a template file?

Question

I am struggling since a couple of days with my problem now and I have no idea what else I can do to come to a stage of enlightenment.

In Drupal 8 I have a content type called "Release" and a content type "Article" which, among others, contains Reviews of Releases. So in Releases I created an entity reference field called "Review" which references Article content type.

For index pages I could create views of Articles and there I pretty easy could integrate the fields of the referencing release entity via the Relations section in views administration. There the reverse direction of a relationship is not a problem.

How do I access the fields of the release in a node--article.html.twig template?

Edited due to character limitation in the comments section (I hope this is allowed): Thank you so much, @JeremyM4an, but there was a little misunderstanding due to my bad explanation of the problem. I should have mentioned that article has a reference to a taxonomy term, called field_post_category.

So a review is an article with field_post_category == 'Review' and finally a release has an entity reference field, called field_review, referring to article. After reading your answer I tried this:

$category_field = $node->get('field_post_category');
$category_field = $category_field->getValue();
if( isset($category_field[0]['target_id']) && $category_field[0]['target_id'] ){
  $term = taxonomy_term_load($category_field[0]['target_id']);
  if($term && $term->get('name')->value == 'Reviews'){
    $release = \Drupal::entityQuery('node')
    ->condition('type', 'release')
    ->condition('field_review.entity:node.nid', $node->id())
    ->execute();
    // Load release node and store in variables.
    $variables['release'] = Node::load(array_values($release)[0]);
  }
}

But this does not work.

Answer 1

You can get the "relationships" to your referencing node in a preprocess function, in your theme's mytheme.theme file:

function mytheme_preprocess_node(&$variables) {
  if (!empty($variables['node'])) {
    $node = $variables['node'];
    if ($node->getType() === 'article') {

      // Get the review by article node id.
      $review = \Drupal::entityQuery('node')
        ->condition('type', 'review')
        ->condition('field_article', $node->id())
        ->execute();

      // Get release by review node id.
      $release = \Drupal::entityQuery('node')
        ->condition('type', 'release')
        ->condition('field_review', array_pop($review))
        ->execute();

      // Load release node and store in variables.
      $variables['release'] = Node::load(array_values($release)[0]);
    }
  }
}

Then you can access the fields in your template:

{{ release.field_name.value }}