What are the key steps involved in handling PayPal transactions and updating the status of purchased items in a PHP application?
When handling PayPal transactions in a PHP application, it is important to ensure that the status of purchased items is updated accordingly. This can be achieved by integrating PayPal's IPN (Instant Payment Notification) system, which will notify your application of any transaction updates. Upon receiving the IPN notification, you can then update the status of purchased items in your database.
// Sample code to handle PayPal IPN notification and update item status
// Step 1: Validate IPN notification
$raw_post_data = file_get_contents('php://input');
$raw_post_array = explode('&', $raw_post_data);
$myPost = array();
foreach ($raw_post_array as $keyval) {
$keyval = explode('=', $keyval);
if (count($keyval) == 2) {
$myPost[$keyval[0]] = urldecode($keyval[1]);
}
}
$req = 'cmd=_notify-validate';
foreach ($myPost as $key => $value) {
$value = urlencode(stripslashes($value));
$req .= "&$key=$value";
}
// Step 2: Send validation request to PayPal
$ch = curl_init('https://www.sandbox.paypal.com/cgi-bin/webscr');
curl_setopt($ch, CURLOPT_HTTP_VERSION, CURL_HTTP_VERSION_1_1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, $req);
curl_setopt($ch, CURLOPT_SSL_VERIFYPEER, 1);
curl_setopt($ch, CURLOPT_SSL_VERIFYHOST, 2);
curl_setopt($ch, CURLOPT_FORBID_REUSE, 1);
curl_setopt($ch, CURLOPT_HTTPHEADER, array('Connection: Close'));
if (!($res = curl_exec($ch))) {
curl_close($ch);
exit;
}
curl_close($ch);
// Step 3: Process IPN response
if (strcmp($res, "VERIFIED") == 0) {
// IPN is verified, update item status in database
$item_id = $_POST['item_number'];
$status = $_POST['payment_status'];
// Update item status in database based on $item_id and $status
} else if (strcmp($res, "INVALID") == 0) {
// IPN is invalid, log for investigation
}