app\models\Activity::key PHP 메소드

    public function key()
    {
        return sprintf('%s-%s-%s', $this->activity_type_id, $this->client_id, $this->created_at->timestamp);
    }

 /**
  * @param Client $client
  * @return array
  */
 public function transform(Activity $activity)
 {
     return ['id' => $activity->key(), 'activity_type_id' => $activity->activity_type_id, 'client_id' => $activity->client->public_id, 'user_id' => $activity->user->public_id + 1, 'invoice_id' => $activity->invoice ? $activity->invoice->public_id : null, 'payment_id' => $activity->payment ? $activity->payment->public_id : null, 'credit_id' => $activity->credit ? $activity->credit->public_id : null, 'updated_at' => $this->getTimestamp($activity->updated_at)];
 }