Hello,

Ronald Gelbard Doppler I have custom created a function that effectively links an email and password with an anonymous user. This function can be used for login or signup anonymous users. The full code below.

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How to implement that:

Login or Signup Anonymous User
Trigger this action on the signup page instead of the default signup action. You should pass email, password, and username to this action.
Alternatively, you can edit this action to provide other user details such as language and currency. The function updates the user document in Firestore. Please remember to define the arguments.

Error handling:

The function returns null if everything is successful. You should add a conditional action after this action that will continue if the output is not set or empty or display a snackbar or other error modal in case of an error code.

Here are the potential FirebaseAuthException error codes that may arise in this function:

email-already-in-use: The email is already associated with another account.
invalid-credential: The provided credential is malformed or has expired.
operation-not-allowed: Email/password accounts are not enabled in Firebase settings.
weak-password: The password is too weak.
requires-recent-login: The user’s last sign-in time does not meet the security threshold.
user-disabled: The user’s account has been disabled by an administrator.

The error codes from the function:

unknown-error
not-anonymous-or-not-signed-in

If you are using a local run, you can also view logs in the Device Log.

I hope this solution will help you resolve your issue.

// Automatic FlutterFlow imports\nimport '/backend/backend.dart';\nimport '/backend/schema/structs/index.dart';\nimport '/backend/schema/enums/enums.dart';\nimport '/actions/actions.dart' as action_blocks;\nimport '/flutter_flow/flutter_flow_theme.dart';\nimport '/flutter_flow/flutter_flow_util.dart';\nimport '/custom_code/actions/index.dart'; // Imports other custom actions\nimport '/flutter_flow/custom_functions.dart'; // Imports custom functions\nimport 'package:flutter/material.dart';\n// Begin custom action code\n// DO NOT REMOVE OR MODIFY THE CODE ABOVE!\n\nimport 'package:firebase_auth/firebase_auth.dart';\nimport 'package:cloud_firestore/cloud_firestore.dart';\n\nFuture<String?> linkAnonymousUserWithEmail(\n  String email,\n  String password,\n  String displayName,\n) async {\n  // Add your function code here!\n\n  print('--- Start: Linking Anonymous User ---');\n\n  final FirebaseAuth auth = FirebaseAuth.instance;\n  final FirebaseFirestore firestore = FirebaseFirestore.instance;\n  User? user = auth.currentUser;\n\n  if (user != null && user.isAnonymous) {\n    try {\n      // Create email/password credential\n      AuthCredential credential =\n          EmailAuthProvider.credential(email: email, password: password);\n\n      // Link the anonymous user with the email/password credential\n      UserCredential userCredential = await user.linkWithCredential(credential);\n\n      // Update the displayName in Firebase Auth\n      await userCredential.user?.updateDisplayName(displayName);\n\n      // Reload the user to ensure the latest profile information is fetched\n      await userCredential.user?.reload();\n\n      // Fetch the updated user object\n      User? updatedUser = auth.currentUser;\n\n      if (updatedUser != null) {\n        // Update Firestore user document with email, name and linkedAt timestamp \n        await firestore.collection('users').doc(updatedUser.uid).set({\n          'email': updatedUser.email,\n          'display_name': updatedUser.displayName,\n          'linkedAt': FieldValue.serverTimestamp(),\n        // Here you add other field if needed (remeber to define it in arguments)e.g. 'language': language,\n        }, SetOptions(merge: true));\n      }\n\n      print('--- End: Linking Anonymous User - SUCCESS ---');\n      return null; // Indicate success\n    } on FirebaseAuthException catch (e) {\n      print('--- End: Linking Anonymous User - FIREBASE ERROR ---');\n      return e.code; // Return FirebaseAuthException error code\n    } catch (e) {\n      print('--- End: Linking Anonymous User - GENERAL ERROR ---');\n      return 'unknown-error'; // Return a generic error code for other exceptions\n    }\n  } else {\n    print(\n        '--- End: Linking Anonymous User - NOT ANONYMOUS OR NOT SIGNED IN ---');\n    return 'not-anonymous-or-not-signed-in'; // Return specific error for invalid user state\n  }\n}\n

How can I convert an anonymous Firebase user to a named user and keep his records?