PayPal: MerchantSDK DoExpressCheckoutPaymentResponse validation - php

Question

What are the fields I should validate in DoExpressCheckoutPaymentResponse or is it necessary to validate it?
I was validating the :
$response->DoExpressCheckoutPaymentResponseDetails->PaymentInfo->SellerDetails->PayPalAccountID
But it does not seem to be always provided.
I also validate the GrossAmount (value and currencyCode) and TransactionID in a similar way.

Answer 1

The only thing you need to do is to check the ACK value of the DoExpressCheckout API call.
If the ACK=Success, the transaction completed successfully.
With the PHP merchant SDK you can do something like this:
$DoECReq = new DoExpressCheckoutPaymentReq();
$DoECReq->DoExpressCheckoutPaymentRequest = $DoECRequest;
try {
/* wrap API method calls on the service object with a try catch */
$DoECResponse = $paypalService->DoExpressCheckoutPayment($DoECReq);
} catch (Exception $ex) {
include_once("../Error.php");
exit;
}
if(isset($DoECResponse)) {
echo "<table>";
echo "<tr><td>Ack :</td><td><div id='Ack'>$DoECResponse->Ack</div> </td></tr>";
if(isset($DoECResponse->DoExpressCheckoutPaymentResponseDetails->PaymentInfo)) {
echo "<tr><td>TransactionID :</td><td><div id='TransactionID'>". $DoECResponse->DoExpressCheckoutPaymentResponseDetails->PaymentInfo[0]->TransactionID."</div> </td></tr>";
}
echo "</table>";
echo "<pre>";
print_r($DoECResponse);
echo "</pre>";
}
It's advised by PayPal to integrate the IPN as well. I always rely on them before validating the payment.
There is more information about how to implement them on the PayPal developer website: https://developer.paypal.com/webapps/developer/docs/classic/products/instant-payment-notification/