How to check if an article is referenced from a collection? I have a collection content type which is just a list of EntityReferences to articles. 

When I am loading an article, how can I use the Entity API to check if it belongs to one or more collections? 

Previously I would query the DB, but I wonder if there is a more idiomatic way?
To load all collection id's, which have a reference to $article_id:

$collection_ids = \Drupal::entityQuery('node')
  -&gt;condition('type', 'collection')
  -&gt;condition('field_article_ref', $article_id)
  -&gt;execute();
if ( count($collection_ids) &gt; 0 ) {
  echo "the article $article_id is referenced in one or more collections";
}