The Underscore Archives

On 17 Jan 2012, at 13:21, Steve Kirtley wrote:

> Hi all,
> 
> Being a little lazy - but can't spot the answer in the paypal documentation
> and short on time....
> 
> When using the very simple paypal cart to take payments is there some sort
> of call back to programatically know payment was successful?

IPN's what you're looking for.

The idea is that you pass a URL to PayPal which they will hit when payment occurs (or another event happens).  Your script then immediately passes the POST data back to PayPal to check that it's legit, and then use it.

In PHP:

  $input_data = 'cmd=_notify-validate&'.file_get_contents("php://input");

  $paypal_reply = http_post_data('http://www.paypal.com/cgi-bin/webscr', $input_data);

  if(preg_match('/VERIFIED/',$paypal_reply)) {/* seems okay.. work with $_POST now */}
  else if(preg_match('/INVALID/',$paypal_reply)) {/* definitely borked */}
  else {/* possible temporary error? */}

Coincidentally, I just cut-and-pasted most of that out of the Emacs window I have focused on my main monitor right now :)

Tom

-- 
Tom Gidden
http://gidden.net/tom