How to get all node entities tagged with a specific term?

Question

For a given taxonomy term in D8, is there any API function/method that returns all node entities that reference it?

Answer 1

You can use loadByProperties() to get all node entities that reference $term_id:

$nodes = \Drupal::entityTypeManager()->getStorage('node')->loadByProperties([
  'field_tags' => $term_id,
]);

Answer 2

Easiest way I think is to query database taxonomy_index table keeps record of what node is tagged with what term

function _get_nodes_by_term($term_id) {
  $query = \Drupal::database()->select('taxonomy_index', 'ti');
  $query->fields('ti', ['nid']);
  $query->condition('ti.tid', $term_id);
  $nodes = $query->execute()->fetchAssoc();
  return $nodes;
}

dpm(_get_nodes_by_term(<term_id>));

Drupal Core does it by views.
Out the box term page display is created by views so if you visit admin/structure/views/view/taxonomy_term, this view is responsible to show all tagged content by given term, which is essentially running database query.

Answer 3

If you have multiple term ids you can pass an array of the ids instead of just a single value.

$term_ids =  array (1,2,3);
$nodes = \Drupal::entityTypeManager()->getStorage('node')->loadByProperties([
  'field_tags' => $term_ids,
]);

Answer 4

If your nodes not having revision then this code will work, by default it will return the first revision

  $nodes = \Drupal::entityTypeManager()->getStorage('node')->getQuery()
 ->condition('field_tags', $termId)
 ->execute();

If your nodes have multiple revisions, To get the nodes by the latest tagged revision. you need to use the following code

$nodes = \Drupal::entityTypeManager()->getStorage('node')->getQuery()
->latestRevision()
->condition('field_tags', $termId, '=')
->execute();

if you have multiple values then you can use array

 $termIds = [3,56,456];
 $nodes = \Drupal::entityTypeManager()->getStorage('node')->getQuery()
 ->latestRevision()
 ->condition('field_tags', $termIds)
 ->execute();