Can I set custom UID when using signInWithPhoneNumber of Firebase Auth in javascript when user first logs in?

Question

I want document-ids of user database to be their phoneNumber+userName. For that purpose I want to set custom UID for the user when he first logs in.

Answer 1

There is no way to control the UIDs generated by Firebase's built-in providers. If you want to control the UID, you will have to create your own provider. I'd recommend against using any part of the credentials as the UID though, as you want a UID to be stable and not have to change it when someone gets (for example) a new phone number, or wants to be known by a different user name.

This has been covered a few times before, so I recommend also checking out:

• how to create FireBase new users with custom UID with flutter
• Custom UID for each user created for Firestore
• Create users with custom uid as key with React Native Firebase
• Can i set a custom uid in firebase anonymous auth with java?
• and more of these search results