Drupal Facet API Custom Hierarchy Callback for Entity Reference Fields

gistfile1.txt

/**
 * Implements hook_facetapi_facet_info_alter().
 */
function hook_facetapi_facet_info_alter(array &$facet_info, array $searcher_info) {
  foreach ($facet_info as $name => $facet) {
    $name = 'field_parent';
    if ($name == $name) {
      $facet_info[$name]['hierarchy callback'] = 'hook_facets_entity_reference_hierarchy';
    }
  }
}

function hook_entity_reference_hierarchy(array $values) {
  $query = new EfqHelper('node');
  $query->propertyCondition('type', 'node_type')
    ->fieldCondition('field_parent', 'target_id', $values, 'IN')
    ->addMetaData('account', user_load(1)); // Run the query as user 1.
  $results = $query->result();
  $parents = array();
  foreach ($results as $nid => $node) {
    $w = entity_metadata_wrapper('node', $node);
    $parent_node = $w->field_parent->value();
    if ($parent_node) {
      $parent_nid = $parent_node->nid;
      $parents[$nid][] = $parent_nid;
    }
  }
  return $parents;
}