public function toXMLString() { $str = ''; $str .= '<ns:DoDirectPaymentReq>'; if ($this->DoDirectPaymentRequest != null) { $str .= '<ns:DoDirectPaymentRequest>'; $str .= $this->DoDirectPaymentRequest->toXMLString(); $str .= '</ns:DoDirectPaymentRequest>'; } $str .= '</ns:DoDirectPaymentReq>'; return $str; }