Add value from Sharedpreferences in variable (stateful widget) - flutter

Question

I saved the data using SharedPreferences, when my app is starting i try check type of user "client" or "company" after that wil be shown screen.
Future<void> setTypeClient() async {
final _storage = SharedPreferences.getInstance();
final storage = await _storage;
storage.setString('type_user_db', 'client');
}
My app is starting
I have variable
var typeUser = ' ' ; and use it when I determine which screen to display
Аfter I get the data from SharedPreferences, I need to put value in this variable
But i have an error, cause variable remains empty
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../views/home_view.dart';
import '../views/auth/client_auth_view.dart';
import '../views/auth/company_auth_view.dart';
import '../views/auth/company_reg_view.dart';
import '../views/client/client_view.dart';
import '../views/company/company_view.dart';
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return const MyAppBody();
}
}
class MyAppBody extends StatefulWidget {
const MyAppBody({Key? key}) : super(key: key);
#override
State<MyAppBody> createState() => _MyAppBodyState();
}
class _MyAppBodyState extends State<MyAppBody> {
Future<void> getTypeUser() async {
final storage = await SharedPreferences.getInstance();
final type = storage.getString('type_user_db');
setState(() {
typeUser = type!;
});
}
var typeUser = '';
Map<String, Widget> screenByUser = {
'client': const ClientView(),
'company': const CompanyView(),
};
bool isLogOut = true;
#override
void initState() {
if (FirebaseAuth.instance.currentUser != null) {
getTypeUser();
setState(() {
isLogOut = false;
});
super.initState();
} else {
return;
}
}
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Well Plus',
debugShowCheckedModeBanner: false,
routes: {
'/main': (context) => const HomeView(),
'/auth_client': (context) => const AuthClientView(),
'/auth_company': (context) => const AuthCompanyView(),
'/reg_company': (context) => const RegCompanyView(),
'/client': (context) => const ClientView(),
'/company': (context) => const CompanyView(),
},
home: isLogOut ? const HomeView() : screenByUser[typeUser],
);
}
}
update
import 'package:firebase_auth/firebase_auth.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import '../views/home_view.dart';
import '../views/auth/client_auth_view.dart';
import '../views/auth/company_auth_view.dart';
import '../views/auth/company_reg_view.dart';
import '../views/client/client_view.dart';
import '../views/company/company_view.dart';
class MyApp extends StatelessWidget {
const MyApp({Key? key}) : super(key: key);
#override
Widget build(BuildContext context) {
return const MyAppBody();
}
}
class MyAppBody extends StatefulWidget {
const MyAppBody({Key? key}) : super(key: key);
#override
State<MyAppBody> createState() => _MyAppBodyState();
}
class _MyAppBodyState extends State<MyAppBody> {
Future<void> getTypeUser() async {
final storage = await SharedPreferences.getInstance();
final type = storage.getString('type_user_db');
setState(() {
typeUser = type!;
});
}
var typeUser = '';
Map<String, Widget> screenByUser = {
'client': const ClientView(),
'company': const CompanyView(),
};
bool get isLogOut => typeUser.isEmpty;
#override
void initState() {
if (FirebaseAuth.instance.currentUser == null) {
getTypeUser();
setState(() {
isLogOut = false;
});
super.initState();
} else {
return;
}
}
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Well Plus',
debugShowCheckedModeBanner: false,
routes: {
'/main': (context) => const HomeView(),
'/auth_client': (context) => const AuthClientView(),
'/auth_company': (context) => const AuthCompanyView(),
'/reg_company': (context) => const RegCompanyView(),
'/client': (context) => const ClientView(),
'/company': (context) => const CompanyView(),
},
home: isLogOut ? const HomeView() : screenByUser[typeUser],
);
}
}
error in
setState(() {
isLogOut = false;
});
error screen
enter image description here

Answer 1

To solve this issue we have to clarify synchronous and asynchronous operations.
Initialating you widget with initState and next build method called one by one in synchronous way but getUser is asynchronous.
This is meant that you specify isLogOut before you setting the typeUser.
Instead of manually setting the isLogOut property just to change it to getter
bool get isLogOut => typeUser.isEmpty;
And you can guarantee the property will be correct all the time when you requests it.
Enjoy coding