public function getInternal($force_create = false)
{
if ($this->internal_id) {
$internal = self::model($this->internal_type)->findByPk($this->internal_id);
if (!$internal && $force_create) {
$this->internal_id = null;
$internal = new $this->internal_type();
}
return $internal;
} else {
return new $this->internal_type();
}
}