Robot Has No Heart

Paypal Instant Payment Notification lets you know when you have received a paypal payment. Presumably, you then mark an order as paid or something. Do not use the current time as the paid_at date – despite the ‘instant’ in the title it can be many days later. You should use the payment_date provided by paypal. Your accountant will thank you.

But here’s the rub. From the IPN spec, payment_date is:
bq. Time/Date stamp generated by PayPal system [format: “18:30:30 Jan 1, 2000 PST”]

Seen that date format before? No? Didn’t think so. That’s no RFC I’ve seen before. The popular Paypal gem uses Time.parse, but this is incorrect (as of 2.0.0). Observe:

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>> Time.parse("18:30:30 Mar 28, 2008 PST")
=> Fri Mar 28 18:30:30 1100 2008 # Good
>> Time.parse("18:30:30 Feb 28, 2008 PST")
=> Fri Mar 28 18:30:30 1100 2008 # FAIL

Also, Time only has a range of about a week, so that could screw you over come any major system failures (either you or paypal). Also note the payment_date is in PST, which unless you’re on the right side of the US is fairly useless. I recommend the following:

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>> DateTime.strptime("18:30:30 Jan 1, 2000 PST", "%H:%M:%S %b %e, %Y %Z").new_offset(0)
=> Sun, 02 Jan 2000 02:30:30 0000

The un-intuitive new_offset converts to UTC. Patch submitted. I hate you, Paypal.