Hey everyone!

I'm using a Paypal add to cart button for a simple ecommerce website. I had a Paypal IPN handler written in PHP that was successfully working for 'Buy it Now' buttons and purchasing one item at a time. I would run a database query each time to update the store's inventory to reflect the purchase.

Now I'm upgrading this store to a 'cart' version so people could check out with multiple items at a time. Would anyone be able to tell me, in general, how my IPN handler would need to be altered to accommodate this? I'm unsure of what a response from Paypal looks like for a cart purchase as opposed to a buy it now purchase.

Thanks, any help or examples of working IPN cart scripts would be very appreciated! My current code is below..

    // Paypal POSTs HTML FORM variables to this page
// we must post all the variables back to paypal exactly unchanged and add an extra parameter cmd with value _notify-validate

// initialise a variable with the requried cmd parameter
$req = 'cmd=_notify-validate';

// go through each of the POSTed vars and add them to the variable
foreach ($_POST as $key => $value) {
$value = urlencode(stripslashes($value));
$req .= "&$key=$value";
}

// post back to PayPal system to validate
$header .= "POST /cgi-bin/webscr HTTP/1.0\r\n";
$header .= "Content-Type: application/x-www-form-urlencoded\r\n";
$header .= "Content-Length: " . strlen($req) . "\r\n\r\n";

// In a live application send it back to www.paypal.com
// but during development you will want to uswe the paypal sandbox

// comment out one of the following lines

$fp = fsockopen ('www.sandbox.paypal.com', 80, $errno, $errstr, 30);
//$fp = fsockopen ('www.paypal.com', 80, $errno, $errstr, 30);

// or use port 443 for an SSL connection
//$fp = fsockopen ('ssl://www.paypal.com', 443, $errno, $errstr, 30);


if (!$fp) {
// HTTP ERROR
}
else
{
  fputs ($fp, $header . $req);
  while (!feof($fp)) {
    $res = fgets ($fp, 1024);
    if (strcmp ($res, "VERIFIED") == 0) {


      $item_name = stripslashes($_POST['item_name']);
      $item_number = $_POST['item_number'];
      $item_id = $_POST['custom'];  
      $payment_status = $_POST['payment_status'];
      $payment_amount = $_POST['mc_gross'];         //full amount of payment. payment_gross in US
      $payment_currency = $_POST['mc_currency'];
      $txn_id = $_POST['txn_id'];                   //unique transaction id
      $receiver_email = $_POST['receiver_email'];
      $payer_email = $_POST['payer_email'];
      $size = $_POST['option_selection1'];
      $item_id  = $_POST['item_id'];
      $business = $_POST['business'];



      if ($payment_status == 'Completed')  {  
// UPDATE THE DATABASE      


      }