我是Paypal的新手并尝试使用paypal付款。我找到代码在我的网站上显示购买按钮，它成功地将我重定向到paypal。成功付款后，我想将用户trasnaction id存储到我的数据库中。但作为回应我没有得到交易ID。
这是我的代码：
<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="business_email@gmail.com">
<input type="hidden" name="item_name" value="Job Post">
<input type="hidden" name="item_number" value="1">
<input type="hidden" name="amount" value="25">
<input type="hidden" name="quantity" value="1">
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="cancel_return" value="<?php echo base_url('account/paypal_cancel');?>">
<input type="hidden" name="notify_url" value="<?php echo base_url('account/paypal_return');?>">
<input type="hidden" name="return" value="<?php echo base_url('account/paypal_return');?>">
<input type="image" class="hidden" name="submit" name="paypal_submit" id="paypal_submit"
src="https://www.paypalobjects.com/en_US/i/btn/btn_buynow_LG.gif"
alt="PayPal - The safer, easier way to pay online">
</form>
付款成功后，我得到了回复：
Array
(
[mc_gross] => 25.00
[protection_eligibility] => Eligible
[address_status] => confirmed
[payer_id] => K7MH34Q4ZNN12
[tax] => 0.00
[address_street] => 1 Main St
[payment_date] => 23:25:32 Aug 03, 2016 PDT
[payment_status] => Completed
[charset] => windows-1252
[address_zip] => 95131
[first_name] => Payer First name
[mc_fee] => 1.28
[address_country_code] => US
[address_name] => Name
[notify_version] => 3.8
[custom] =>
[payer_status] => verified
[business] => business_email@gmail.com
[address_country] => United States
[address_city] => San Jose
[quantity] => 1
[payer_email] => payer_email@gmail.com
[verify_sign] => AFcWxV21C7fd0v3bYYYRCpSSRl31Apes4ffYPHmXs3U0H9m6oiBFZWDe
[txn_id] => 4HH86447NJ982154T
[payment_type] => instant
[last_name] => Last Name
[address_state] => CA
[receiver_email] => business_email@gmail.com
[payment_fee] => 1.28
[receiver_id] => C4VX55Z5QJG87
[txn_type] => web_accept
[item_name] => Job Post
[mc_currency] => USD
[item_number] => 1
[residence_country] => US
[test_ipn] => 1
[handling_amount] => 0.00
[transaction_subject] =>
[payment_gross] => 25.00
[shipping] => 0.00
[auth] => A5eWy6N2pRotb5qNnmxnnEWAabmNZfgr0pGGMFWYVoXqrcmQpINk7nAB0fNCv0m66XgcwMbCVIWqtW0q7yldjHg
)
我想要交易ID，但响应中没有交易ID。
任何人都可以帮助我，我如何使用paypal响应获得交易ID。
由于