Post to database and to paypal using one button - php

Question

I'm actually stuck, sending a form post request to multiple action receiver.
What am I trying to do?
I'm trying to send an post request to my database and to paypal at the same time using one button.
After the user submitted the form, I want my PHP script to post those informations to the database before redirecting to paypal. To work with those sent informations.
My actual code:
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="item_name" id="item_name" value="Helpful.ninja coins"/>
<input type="hidden" name="business" value="pr0bpayment#gmail.com">
<input type="hidden" name="return" value="http://helpful.ninja/?username=payment_complete=1">
<input type="hidden" name="image_url" value="http://helpful.ninja/assets/images/logo_dark.png">
<input type="hidden" name="no_shipping" value="1">
<input type="hidden" name="amount" class="amountToPay" value="">
<input type="hidden" name="no_note" value="1">
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="bn" value="PP-BuyNowBF">
<button type="submit" name="submit" alt="PayPal - The safer, easier way to pay online!" class="btn bg-danger-400">Purchase now <i class="icon-paypal position-right"></i></button>
</form>
<?php
require_once('../handling/database.php');
require_once('../handling/user.class.php');
require_once('../handling/purchase.class.php');
require_once('../handling/config.php');
$user = new user($_SESSION['Username']);
$config = new config();
if(!empty($_POST)){
$purchase = new purchase($user->username, $user->coins, $_POST['coinValue'], $config->coin_price);
$purchase->insert_purchase($user->username, $user->email, $_SERVER['REMOTE_ADDR'], $purchase->ordernumber, $purchase->purchase_amount, $purchase->price);
}
?>
<script type="text/javascript">
$(".coinValue").bind("change paste keyup", function() {
$(".amountToPay").val($(this).val() * <?php echo $config->coin_price; ?>);
});
</script>
So I'm trying to post the following code:
if(!empty($_POST)){
$purchase = new purchase($user->username, $user->coins, $_POST['coinValue'], $config->coin_price);
$purchase->insert_purchase($user->username, $user->email, $_SERVER['REMOTE_ADDR'], $purchase->ordernumber, $purchase->purchase_amount, $purchase->price);
}
to the databse before the user gets redirected to paypal.
Does anyone have an idea how to manage this?

Answer 1

The best option is probably to use one of the other PayPal apis that is designed for this type of thing, but sticking with the simple paypal button api, you can use the fact that the paypal api endpoint will accept the parameters in a get request as well as a post.
So you can post the form to your php handler then perform a header redirect to paypal with the data:
<?php
//php must be at top of file, before ANY output, in order to use header redirect
require_once('../handling/database.php');
require_once('../handling/user.class.php');
require_once('../handling/purchase.class.php');
require_once('../handling/config.php');
$user = new user($_SESSION['Username']);
$config = new config();
if(!empty($_POST)){
$purchase = new purchase($user->username, $user->coins, $_POST['coinValue'], $config->coin_price);
$purchase->insert_purchase($user->username, $user->email, $_SERVER['REMOTE_ADDR'], $purchase->ordernumber, $purchase->purchase_amount, $purchase->price);
//redirect to paypal
header('Location: https://www.paypal.com/cgi-bin/webscr?' . http_build_query($_POST));
die();
}
?>
<!-- post form to itsself, not paypal-->
<form action="" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="item_name" id="item_name" value="Helpful.ninja coins"/>
<input type="hidden" name="business" value="pr0bpayment#gmail.com">
<input type="hidden" name="return" value="http://helpful.ninja/?username=payment_complete=1">
<input type="hidden" name="image_url" value="http://helpful.ninja/assets/images/logo_dark.png">
<input type="hidden" name="no_shipping" value="1">
<input type="hidden" name="amount" class="amountToPay" value="">
<input type="hidden" name="no_note" value="1">
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="bn" value="PP-BuyNowBF">
<button type="submit" name="submit" alt="PayPal - The safer, easier way to pay online!" class="btn bg-danger-400">Purchase now <i class="icon-paypal position-right"></i></button>
</form>