Drupal 7 Push Notification Tokens for Organic Group Members

example.php

<?php

/**
 * Given a group node id, this will return all the push notification tokens
 * belonging to users who are active members of the group.
 * @param $gid
 * @return {Array} An array of push notification strings.
 */
function group_member_push_notification_tokens($gid) {
  $query = db_select("og_membership", "ogm");
  $query->join('push_notifications_tokens', 'tokens', 'ogm.etid = tokens.uid');
  $query->condition("ogm.entity_type", 'user');
  $query->condition("ogm.gid", $gid);
  $query->condition("ogm.group_type", 'node');
  $query->condition("ogm.state", OG_STATE_ACTIVE);
  $query->condition("tokens.type", PUSH_NOTIFICATIONS_TYPE_ID_ANDROID); // @TODO support iOS too!
  $query->fields("tokens", array('token'));
  $result = $query->execute();
  return $result->fetchAll();
}