What is the simplest way to integrate PayPal & Firebase?

Question

I'd like to create this simple model:

1. user registers and Firebase stores email & password
2. user pays with PayPal to access protected content
3. Firebase gets notified by PayPal the user has paid & logs this
4. paying user logs in with his credentials & Firebase authorizes access to the protected content; non-paying users are denied access

What is the bare minimum amount of functionality needed to leverage Firebase's backend and make this work?

Answer 1

Depends on your exact requirements (ie, are 5 or 15 minute delays acceptable) but you can get started super quickly using Zapier

https://zapier.com/zapbook/firebase/paypal/

You would setup the zap using your secret firebase and paypal keys, setting the zap to update a property on the user's profile (be sure to use Firebase security rules to limit write access to that property) which says they have paid.