How to handle leap year with firestore rules?

Question

My goal is allow users to write document which calculate age from birthday only between 16 to 100, I am consider using request.time - duration but duration is not support years so I can't just simply use request.time - duration.value(16, 'y') to achive this. Then I am consider just hardcode 16 years to millsec but just can't figure out how to deal with leap year. Anyone got better idea to this?

Answer 1

I don't think you'll be able to implement such a complex check with Security Rules language.

What you could do is to use a Cloud Function that would calculate and check the age each time a new document is created and, if the age is under 16, does something like the following options (up to you to decide):

• Delete the doc (and possibly warn the user?)
• Set a flag that excludes it from your queries
• Copy the original document that was created in a "waiting" collection to the genuine collection
• ...

We use JavaScript or TypeScript in Cloud Functions for Firebase so you'll be able to accurately calculate the age. You could even use a library like moment or dayjs.