public function create($userId=null, $eventLog=null, $eventData=null)
    {
        if(is_null($userId)) throw new \Exception('User ID is required.');
        if(is_null($eventLog)) throw new \Exception('Event Log is required.');
        if(!is_numeric($userId)) throw new \Exception("Invalid User ID.");

        $id = $this->save($this->generateEntity(intval($userId), $eventLog, $eventData));
        return $id;
    }