Flutter : Flutter Shared Preference don't work ,not save username Edit#1 - flutter

Question

I have an app contain login and register system ,the system is working correctly.
the problem is I want to keep user logged in by using flutter_session package but don't work.
first I have preloading page contain checking if user is logged in by using functions below :
void gotoTabPae() {
print('ok');
Future.delayed(const Duration(milliseconds: 3000), () {
Navigator.of(context).pushReplacementNamed('tabs');
});
}
void gotoLoginPage() {
print('no');
Future.delayed(const Duration(milliseconds: 3000), () {
Navigator.of(context).pushReplacementNamed('login');
});
}
getuser() async {
var loginedUser;
SharedPreferences preferences = await SharedPreferences.getInstance();
setState(() {
loginedUser= preferences.getString('username');
});
loginedUser != null ? gotoTabPae() : gotoLoginPage();
}
#override
void initState() {
getuser();
super.initState();
}
when I run the app and login then when I restart the app it must go to 'tabs' page ,but the value of username is always null therefore it load login page ,the login function is :
login() async {
var formdata = formLoginKey.currentState;
if (formdata.validate()) {
formdata.save();
var data = {'username': username.text, 'password': password.text};
var url =xxxx/api/controller/users/login_user.php";
var response = await http.post(url, body: data);
var responsebody = jsonDecode(response.body);
if (responsebody['status'] == 'success') {
SharedPreferences pref = await SharedPreferences.getInstance();
pref.setString('username', username.text);
Navigator.of(context).pushReplacementNamed('tabs');
} else {
_showDialog(context, responsebody['status']);
}
} else {
}
}
But in tabs page it is load the session username corret :
getuser() async {
SharedPreferences preferences = await SharedPreferences.getInstance();
var logineduser = preferences.getString('username');
}
#override
void initState() {
getuser();
super.initState();
}
How can I solve this? where is my mistake ?

Answer 1

Your code is running the getuser() method in the initSate() method that too even before the super.initState();. That is the reason the value is no able to load which makes it null. You should use it in the build function.
Your code might look like this:
#override
Widget build(BuildContext context) {
var loginedUser;
loginedUser = await FlutterSession().get('username');
loginedUser != null ? return ClassName()(tabs.dart) : return ClassName()(login.dart);
}

Answer 2

I think that in your login function, pref.setString('username', username.text) is run before the response is received. Can you try this:
http.post(url, body: data).then((response) {
var responsebody = jsonDecode(response.body);
if (responsebody['status'] == 'success') {
SharedPreferences pref = await SharedPreferences.getInstance();
pref.setString('username', username.text);
Navigator.of(context).pushReplacementNamed('tabs');
}
});
and let me know the result?