Home Integration Methods PayPal Express Checkout (IPN used by other script)

PayPal Express Checkout (IPN used by other script)

PayPal Express Checkout integrates using IPN callback even if the callback is used by other system (e.g. shopping cart).
Note! This is description of integration with PayPal Express Checkout if you use PayPal buttons on your web pages. If you use PayPal as a processing system in your shopping cart, use the method for integrating with shopping cart, not these steps.
1
PayPal button
Now add the following code into EVERY PayPal button form
This will ensure that referrer will be stored to the custom field.
2
Example
Example of updated PayPal form:

<!-- Begin PayPal Button -->
<form action="https://www.paypal.com/cgi-bin/webscr" method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="paypalemail@yoursite.com">
<input type="hidden" name="undefined_quantity" value="1">
<input type="hidden" name="item_number" value="Product Name">
<input type="hidden" name="amount" value="19.95">
<input type="hidden" name="image_url" value="https://yoursite.com/images/paypaltitle.gif">
<input type="hidden" name="no_shipping" value="1">
<input type="hidden" name="return" value="http://www.yoursite.com/paypalthanks.html">
<input type="hidden" name="cancel_return" value="http://www.yoursite.com">
<input type="hidden" name="custom" value="" id="pap_dx8vc2s5">
<script id="pap_x2s6df8d" src="http://www.yoursite.com/affiliate/scripts/notifysale.php" type="text/javascript">
</script>
<input type="image" src="http://images.paypal.com/images/x-click-but5.gif" border="0" name="submit">
</form>
<!-- End PayPal Button -->
3
Integration 2
Now the IPN callback is pointed to your script. This callback has to be forwarded also to PAP4 paypal.php script, which url is http://www.yoursite.com/affiliate/plugins/PayPal/paypal.php. In case, your paypal processing script is in PHP, you can use following code to accomplish that. You can place it at the beginning of your processing file.
This will ensure that whole IPN callback will be forwarded without affecting your original script
This is all that is required. Now whenever there's sale, PayPal Express Checkout will use its IPN function to call our sale tracking script, and system will generate commission for the affiliate.