public function params($requestParams): array
    {
        // apply type and default value for request params
        $params = [];
        foreach ($this->params as $param => $type) {
            if (isset($requestParams[$param])) {
                switch ($type) {
                    case 'bool':
                    case 'boolean':
                        $params[] = (bool)$requestParams[$param];
                        break;
                    case 'int':
                    case 'integer':
                        $params[] = (int)$requestParams[$param];
                        break;
                    case 'float':
                        $params[] = (float)$requestParams[$param];
                        break;
                    case 'string':
                        $params[] = (string)$requestParams[$param];
                        break;
                    case 'array':
                        $params[] = (array)$requestParams[$param];
                        break;
                    default:
                        $params[] = $requestParams[$param];
                        break;
                }
            } elseif (isset($this->values[$param])) {
                $params[] = $this->values[$param];
            } else {
                $params[] = null;
            }
        }
        return $params;
    }