Can not update variable value inside a void method in flutter - flutter

Question

I'm trying to update a variable value inside a void method in flutter, tried using StatefulBuilder but the value does not get changed.
Here is my code:
class HomeScreen extends StatefulWidget {
const HomeScreen({super.key});
#override
State<HomeScreen> createState() => _HomeScreenState();
}
class _HomeScreenState extends State<HomeScreen> {
final user = FirebaseAuth.instance.currentUser;
String type = "";
void checkUser() async {
await FirebaseFirestore.instance
.collection('users')
.doc(user!.uid)
.get()
.then(
(DocumentSnapshot documentSnapshot) {
if (documentSnapshot.exists) {
var data = documentSnapshot.data();
var res = data as Map<String, dynamic>;
if (res["type"] == "Salarié") {
print('Salarié');
} else if (res["type"] == "Auto entrepreneur") {
print('Auto entrrepreneu');
} else {
showDialog<String>(
context: context,
builder: (_) => StatefulBuilder(
builder: (modalContext, modalSetState) => AlertDialog(
title: const Text('Choissisez votre type'),
content: const Text('Choisir votre type de user'),
actions: <Widget>[
TextButton(
onPressed: () {
setState(() {
type = "Salarié";
});
Navigator.pop(context, 'Cancel');
},
child: const Text('Salarié'),
),
TextButton(
onPressed: () {
setState(() {
type = "Auto entrepreneur";
});
Navigator.pop(context, 'OK');
},
child: const Text('Auto-entrepreneur'),
),
],
),
));
return FirebaseFirestore.instance
.collection("users")
.doc(user!.uid)
.update({
"type": type,
});
}
} else {}
},
);
}
#override
void initState() {
super.initState();
checkUser();
}
#override
Widget build(BuildContext context) {
return Scaffold(...);
It's all inside a StatefulWidget though, I'm not sure whether this is the correct way to do this because the value does not get changed! I appreciate your help.
edit: I'm calling this method inside the initState()

Answer 1

showDialog is not a synchronous operation and the code basically sends the dialog and immediately continues. to fix that, I had to add async and await, and it worked like a charm.