$field && $this->$field == $userId) { return true; } } return false; } /** * @param $userId */ public function setUserId($userId) { if (self::hasUserId($userId)) { return; } for ($i=1; $i<=5; $i++) { $field = "user_id{$i}"; if (!$this->$field) { $this->$field = $userId; break; } } } /** * @param $userId */ public function removeUserId($userId) { if (!$userId || !self::hasUserId($userId)) { return; } for ($i=1; $i<=5; $i++) { $field = "user_id{$i}"; if ($this->$field && $this->$field == $userId) { $this->$field = null; } } } }