I am implementing a PayPal integration system, I have successfully integrated with PayPal and create a database to store the information.
I am wishing to print a receipt after returning to my successful payment landing page.
But I came to a problem - before submitting to Paypal, I do not store anything (not user, nor anything). What can I do to match with Paypal's return IPN variable?
I do not wish the user to enter username nor email beforehand, I wish to have something that is done backend and is done by the system and not by the user.
All PayPal APIs and transaction creation mechanisms support an order/invoice number (INVNUM) and a 'CUSTOM' variable, both of which can store a unique value at transaction creation time.
The value of both of these variables will then be returned to you in the IPN for reconciliation purposes.