Paypal IPN procedure

I would be grateful for any advice on the above.
I am completing (i hope) my paypal IPN settings, and on completing the transaction I click on the 'Return to Merchant' button, where i get redirected to my 'invalid transaction' page.

The transaction is being verified, so there must be an error on my IPN page

I have configured my paypal IPN page as follows...

Check xaction ID from paypal
If not a duplicate..

Add row to payment table
Add row(s) to cart table
Update stock level of items which were in the cart
Update order status in the order table to 'confirmed'
send an email to myself confirming a valid transaction
go to checkout success page

if xactionID is duplicate
send an email to myself confirming a duplicate transaction
go to duplicate xaction page

if xactionID is invalid
send an email to myself confirming a invalid transaction
go to invalid xaction page

I checked my emails and I am getting 2 emails, one after the other, the first showing invalid transaction, the second showing valid transaction.

my confirm.php page has a return value of my IPN page, and as the transaction is valid, i can't work out why I'm getting the error.

Your return page should not be your IPN page. It should be a different page that simply says thank you for your order.

Thanks Ray

I changed the return value to checkout_success.php.

One thing I have noticed is when i navigate back to my cart page from checkout_success, that cart still has items in it.

Is this because my session id is still active ?

Yes... you can use the clear session server behavior that is part of Cookies toolkit, or just look up code on how to clear a session... it is fairly simple.

Really you would only need to clear the OrderID session variable and clear the shopping cart.

Thanks Ray

I assume then, that if i assign the following...

unset($_SESSION['cartname_OrderID']);

in my checkout_success.php and checkout_failure.php pages, that will sort it, it that right ?

and throw in a:

$YourCartName->ClearCart();

to clear the cart itself also on the success page.

probably overkill, but what i have done is

$_SESSION = array();

to clear all sessions.

it seems to work ok, is this overkill and/or will this approach pose any problems ?

thanks

The only issue is that if you have user login it would log out that user. If you don't use login or if you don't mind logging the user out, that method would work just fine.

Excellent.

Thanks for your help

I have successfully included code to unset all sessions on checkout_success and checkout_failure.

in testing, i have found that if i don't visit these pages after paypal, and just go back to my site, whilst keeping the browser open, my sessions are still active.

Were I to unset the session on the checkout confirm page, would this cause any issues with my IPN validation.

If not, at what point should I unset the session, presumably only when the confirm button is clicked ?