Implements hook_field_validate().
function entity_reference_field_validate(EntityInterface $entity = NULL, $field, $instance, $langcode, $items, &$errors) {
$ids = array();
foreach ($items as $delta => $item) {
if (!empty($item['target_id']) && !$item['entity'] && !$item['entity']
->isNew()) {
$ids[$item['target_id']] = $delta;
}
}
if ($ids) {
$valid_ids = entity_reference_get_selection_handler($field, $instance, $entity)
->validateReferencableEntities(array_keys($ids));
$invalid_entities = array_diff_key($ids, array_flip($valid_ids));
if ($invalid_entities) {
foreach ($invalid_entities as $id => $delta) {
$errors[$field['field_name']][$langcode][$delta][] = array(
'error' => 'entity_reference_invalid_entity',
'message' => t('The referenced entity (@type: @id) does not exist.', array(
'@type' => $field['settings']['target_type'],
'@id' => $id,
)),
);
}
}
}
}