Quote Originally Posted by maddudeonline
Just wondering if i made an online shopping cart that used paypals payment page. How would i tell if they actually completed the transaction and didnt just click return to merchant without completing any payment? I want to know for security measures.
I think he's talking about the shopping cart. He wants it so if they add stuff and check out, the shopping cart can tell wether or not the checkout actually completed successfully. If he was going to offer an ebook, he would want to make sure they actually paid before letting them download. Having to check for the email and then send it isn't very efficient.

Paypal offers and Instant Payment Notification service. They also provide code. Basically, you write a script and have it be your return page. The script will check wether or not you recieved money, call Paypal to verifiy the results, and then decide what to do with the guy visiting the page. This way, if someone finds the return URL and goes to it without paying, the script checks and then won't let them download. Otherwise, it provides a link to the ebook or whatever.

I use this for several things. I have one site that offers items and I want the inventory to be up-to-date in real time. When someone makes a purches, that item is delete from the order page. Another site I have is for members only. It checks wether or not the payment has gone through and if it has, it creates and account and emails the user his password.