Paypal IPN已经过验证。 如果我需要退款该怎么办？

Question

I'm selling from my php site and I accept paypal payments, I've got a limited number of products, buyers have them in their carts, and availability is not enough for them all. If they pay with paypal at the same time I need to refound one of them. Is this approach correct, or is it preferable to check availability before the payment IPN notification?

Answer 1

That sounds like a poor user flow. Once you get verification that an item is sold, reduce your inventory in your database. Before sending them to Paypal, verify that you have enough inventory to fulfill their order.

If you get a scenario where say you have one item left and two users were directed to Paypal to purchase it, whoever you receive notification of successful payment first, gets it. The other, you can do a few things:

1. Place the item on backorder, let the user know when it'll come in with an estimate. When it comes in, send it to them.
2. Allow the user to choose whether they want the backorder, or to cancel their order, in which case they get a refund
3. If, once a product sells out, there are none left forever, you can immediately issue a refund.