How to check if the Firebase user has recently signed in in a Flutter app

edn 0
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I need to implement the function that a Firebase user in my app can delete his/her account if s/he wants to. Here is the account deletion function from Flutter for Firebase:

try {
  await FirebaseAuth.instance.currentUser!.delete();
} on FirebaseAuthException catch (e) {
  if (e.code == 'requires-recent-login') {
    print('The user must reauthenticate before this operation can be executed.');
  }
}

In some cases, it may happen that the user had signed in for a long time ago, which will cause the exception of 'requires-recent-login'.

Here is my actual implementation in my app:

  Future<String> deleteUserDataFromDatabase() async {
    try {
      // First, delete the user profile from DB
      await _firestore
          .collection('app_users')
          .doc(_auth!.currentUser!.uid)
          .delete();
  // Lastly, delete the Authentication profile
  User? user = _auth!.currentUser;
  await user!.delete();
} on Exception catch (e) {
  //print(e);
  return Future.value(e.toString());
}

return Future.value('SUCCESS');
  }
}

As you see, before deleting the user with the delete() function, I first delete the user profile data from Firestore DB. I need to do so because I set such security rules that the user itself is the only one who can delete his/her profile information in the database, not anyone else.

If the user has recently signed in, there is no problem, everything goes smoothly. But if the user has not recently signed in, then the user profile info is deleted from DB but not the Firebase authentication user account.

It is not an option to delete the Firebase account first, then the user profile information _auth!.currentUser! becomes null after running the await user!.delete().

How can I overcome this problem?

In Flutter, is there a way to detect whether the Firebase user has recently signed in or not? It would be great if it was possible to detect it.

Additionally, is there a way to force user account deletion even if the user has not signed in very recently?

firebase-authentication dart firebase flutter
1 Answers

firebaser here

The exact time is determine by the server, is intentionally not documented, and can change at any time. There is no way to force deletion (or other sensitive operations) in this case, as that is intentionally trying to prevent such operations until it has confirmed the user's identity.

As others have commented, the correct flow is to try and delete the user, and then handle the error you get.

For the database flow, you have a few options:

  • Mark the document as pending deletion (by writing a specific field value for that purpose), and then permanently delete it once the user account is deleted.
  • Run a cleanups script periodically that either checks all documents to see if the user still exists, or only checks the ones that were marked pending deleted in the previous approach.
  • Use an onDelete Cloud Function that automatically triggers on account deletion.
  • Run the entire operation of deleting the document and account in a Cloud Function, which doesn't have to abide by the recency requirement (as it is a trusted environment).
Frank van Puffelen0
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