Adding referencing entities using hook_entity_property_info_alter

Question

I have a custom entity "Matching" with a multi value field entity reference jobs that references a node of type job.

function custom_alters_entity_property_info_alter(&$info) {
  $info['node']['properties']['referencing_matching'] = array(
    'label' => t('Referencing matching'),
    'type' => "entities",
    'description' => t("Matchings referecing a job"),
    'getter callback' => 'get_referencing_matching'
  );
}

function referencing_matching($node) {
  if($node->type == "job"){
    $query = new EntityFieldQuery();
    $query->entityCondition('entity_type', 'matching')
          ->fieldCondition('field_job_id', 'target_id', $node->nid, '=');
    $result = $query->execute();
    if ($result) {
      return $result;
    }
}

the "getter callback" isn't expecting an id rather than an array

Answer 1

It looks like you are trying to add a multi-valued entity reference property to a standard node entity. If that's the case, I think you first need to declare the property as multi-valued in hook_entity_info_alter() via the 'type' entry:

$info['node']['properties']['referencing_matching'] = array(
  'label' => t('Referencing matching'),
  'type' => 'list<matching>',
  'description' => t("Matchings referecing a job"),
  'getter callback' => 'get_referencing_matching'
);

See the hook_entity_property_info() notes for more on that.

Then, in the getter callback I believe you need to return a list of entity ids, something like:

if ($node->type == "job"){
  $query = new EntityFieldQuery();
  $query->entityCondition('entity_type', 'matching')
        ->fieldCondition('field_job_id', 'target_id', $node->nid, '=');
  $result = $query->execute();
  if (!empty($result['matching'])) {
    return array_keys($result['matching']);
  }
}

I have not tested that specific code, but this was the pattern that I used in a similar example of my own.