I have already created a push notification system using firebase. It generates and saves a token for a user, then upon login displays their subscription status. It works fine, unfortunately it’s only one device per user, the most recent device they logged in on. I’d like to allow for multiple devices per user.
I’m assuming firebase uses some ID unique to each device to generate a token. If I’m wrong in that assumption, please point me in the right direction.
As Doug commented, since FCM doesn't associate its tokens with users, this is probably some limitation in your implementation.
You'll want to allow multiple ID tokens per user in your database, and then send to all tokens for the current user. If the device/app install can be shared between users, you'll want to remove the association between the user and the token for that installation when the user signs out/a new user signs in.
On associating tokens with users, see:
And then finally you'll also want to clean up any tokens that FCM flags as not valid anymore, as otherwise you'll keep adding more and more tokens, which may not be valid anymore.
On deleting expired tokens, see:
