public function getData()
{
$this->validate('app_id', 'mch_id');
if (!$this->getTransactionId() && !$this->getOutTradeNo()) {
throw new InvalidRequestException("The 'transaction_id' or 'out_trade_no' parameter is required");
}
$data = array('appid' => $this->getAppId(), 'mch_id' => $this->getMchId(), 'transaction_id' => $this->getTransactionId(), 'out_trade_no' => $this->getOutTradeNo(), 'nonce_str' => md5(uniqid()));
$data = array_filter($data);
$data['sign'] = Helper::sign($data, $this->getApiKey());
return $data;
}