I'm configuring a PayPal IPN listener from this tutorial and ipnlistener.php.
When I need a user to pay, I show him this form
<form name="_xclick" action="https://www.sandbox.paypal.com/cgi-bin/webscr"
method="post">
<input type="hidden" name="cmd" value="_xclick">
<input type="hidden" name="business" value="<? echo $myPaypalEmail; ?>">
<input type="hidden" name="currency_code" value="USD">
<input type="hidden" name="item_name" value="Digital Download">
<input type="hidden" name="amount" value="<? echo $price; ?>">
<input type="hidden" name="return" value="THIS URL">
<input type="hidden" name="notify_url" value="myhost.com/ipn.php">
<input type="image" src="http://www.paypal.com/en_US/i/btn/btn_buynow_LG.gif"
border="0" name="submit">
</form>
Following the guide, I correctly receive a POST request to the file ipn.php. I receive a lot of useful data about the payment but my problem is: how can I know which user made the payment?
A "user" is a person registering on my website, giving me personal informations and his/her email address. How can I connect these informations to the POST request I receive back from PayPal? The email used to register on my website may be different from the one used in PayPal.
I can think of 2 solutions:
a) Place a unique user id in the return URL, parse it with $_GET and then... This could hardly solve the problem.
b) Get the payment ID as soon as the transaction starts. But I have no idea on how to do that.
As you can see, my problem is to associate a user with the transaction id. The workflow is:
HTML Form -> Paypal website -> ipn.php
HTML Form has user info while ipn.php receive transaction info: I need the user info to go into ipn.php in order to check if the total has been correctly paid and to perform stuff on the user account. How can I do this?
Many thanks.
