Creating other Users on Firebase Authentication and create a document in the users collection

When using FlutterFlow and firebase you would have found that whenever you want to add other users for accessing your app, you can't with standard features, it allows you to add the user, but will automatically sign you in to that user. Which as we know isn't great for User Experience.

Here's a Custom Action to create a user in Firebase Authentication and to create a document in the "users" Collection.

Create a user through a Custom Action

// Automatic FlutterFlow imports
import '/backend/backend.dart';
import '/flutter_flow/flutter_flow_theme.dart';
import '/flutter_flow/flutter_flow_util.dart';
import '/custom_code/actions/index.dart'; // Imports other custom actions
import '/flutter_flow/custom_functions.dart'; // Imports custom functions
import 'package:flutter/material.dart';
// Begin custom action code
// DO NOT REMOVE OR MODIFY THE CODE ABOVE!

import 'package:firebase_auth/firebase_auth.dart';
import 'package:firebase_core/firebase_core.dart';

Future<String> createClientUser(
    // Parameters
    String emailAddress, //Email from Widget State
    String password, //Password from Widget State
    String randomDocGen, //Random String (min 10 max 25 - upper/lowe/digits)
    String firstName,
    String lastName,
    String displayName,
    String uid,
    String userType,
    DateTime createdTime,
    String dobFull,
    int? dobYear) async {
  //Create the return msg
  String returnmsg = 'Success';
  //created time variable
  DateTime createdTime = DateTime.now(); //
  //Create the secondary app to create the users
  FirebaseApp app = await Firebase.initializeApp(
      name: randomDocGen, options: Firebase.app().options);

  try {
    //Create the user with the email & password provided
    UserCredential userCredential = await FirebaseAuth.instanceFor(app: app)
        .createUserWithEmailAndPassword(
            email: emailAddress, password: password);
    // Set the UID generated to a variable so we can use it later
    String? uid = userCredential.user?.uid;
    // Check if UID is not empy
    if (uid != null) {
      //Get collection reference to create our new user document
      final CollectionReference<Map<String, dynamic>> usersRef =
          FirebaseFirestore.instance.collection('users');

      //Create new user document with the parameters we have (you can add more parameters and just add here the extra)
      usersRef.doc(uid).set({
        'uid': uid,
        'email': emailAddress,
        'created_time': createdTime,
        'first_name': firstName,
        'last_name': lastName,
        'display_name': displayName,
        'user_type': userType,
        'dob_full': dobFull,
        'dob_year': dobYear,
      });
      return returnmsg;
    } else {
      return "Error while creating the UID";
    }
  } on FirebaseAuthException catch (e) {
    return e.code;
  }
}

// Set your action name, define your arguments and return parameter,
// and then add the boilerplate code using the button on the right!