Flutter - FutureBuilder not rebuilding when user logs into Firebase? - firebase

Question

I am trying to fetch my currentUser using FutureBuilder in my main.dart file:
//my auth.dart file
class Auth {
final FirebaseAuth _auth = FirebaseAuth.instance;
Future getUser() {
return _auth.currentUser();
}
}
class MyApp extends StatelessWidget {
Auth auth = Auth();
#override
Widget build(BuildContext context) {
return MaterialApp(
home: FutureBuilder(
future: auth.getUser(),
builder: (context, AsyncSnapshot snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.error != null) {
print("$snapshot.error.toString()");
return Container();
}
if (snapshot.hasData) {
return BottomBar(
firebaseUser: snapshot.data, visibleLogin: false);
} else if (snapshot.data == null) {
return BottomBar(
firebaseUser: null,
visibleLogin: true,
);
}
}
return CircularProgressIndicator();
}),
);
}
}
//Update, tried using StreamBuilder
StreamBuilder<FirebaseUser>(
stream: FirebaseAuth.instance.onAuthStateChanged,
builder: (BuildContext context, snapshot) {
if (snapshot.connectionState == ConnectionState.done) {
if (snapshot.data.uid!=null) {
return BottomBar(
firebaseUser: snapshot.data, visibleLogin: false);
} else {
return BottomBar(
firebaseUser: null,
visibleLogin: true,
);
}
}
return CircularProgressIndicator();
}),
Whenever my user logs in, I pass the user in my bottom navigation bar, which then passes the data to all my pages.
My login is in the same page as my home page, so whenever my user logs in, I want to hide the login part in my home page.
Widget login(bool visibleLogin) {
return Visibility(
visible: visibleLogin,
child: Align(
alignment: Alignment.bottomCenter,
child: Padding(
padding: const EdgeInsets.only(bottom: 78.0),
child: Container(
height: 90,
color: Colors.transparent,
margin: EdgeInsets.fromLTRB(8.0, 0.0, 8.0, 0.0),
child: Container(
child: Container(
margin: EdgeInsets.only(top: 20.0),
child: Column(
children: [
Padding(
padding: EdgeInsets.only(top: 5.0),
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
GestureDetector(
onTap: () => auth.signInWithGoogle(),
child: Container(
padding: EdgeInsets.all(10.0),
child: Icon(
FontAwesome.google,
color: kOrange,
),
),
),
],
),
),
],
),
),
),
),
),
),
);
}
When my user logs in, the UI of my app doesn't get updated automatically by my FutureBuilder, hence I call the onAuthStateChanged listener in my initState() of my homepage:
void isSignedIn() {
_auth.onAuthStateChanged.listen((user) {
if (user != null) {
setState(() {});
} else {
print('no user');
}
});
}
}
After checking, this method is getting triggered, but my UI only gets updated when I shut and relaunch my app. How do I update my UI as soon as my user logs in?

Answer 1

I think this is not possible with FutureBuilder, you have to use StreamBuilder for this Functionality.
As once Future is complete it will not look for any change, where as if you use stream then whenever new data arrives it will change data.
Update:
You even don't need to change any variable or call any method, now just check snap and show screen accordingly. make to check connection status is done because until that time it will return null even user is login.
StreamBuilder(
stream: FirebaseAuth.instance.onAuthStateChanged,
builder: (_, snap) {
if(snap.connectionState == ConnectionState.active){
if(snap.data == null){
// return with out login
}else{
// return login
}
}else{
return CircularProgressIndicator();
}
},
),
Update:
Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
StreamBuilder(
stream: FirebaseAuth.instance.onAuthStateChanged,
builder: (_, snap) {
print(snap.connectionState);
if (snap.connectionState == ConnectionState.active) {
print(snap.data.toString());
if (snap.data == null) {
return Text("not login");
} else {
return Text("login");
}
} else {
return CircularProgressIndicator();
}
},
),
RaisedButton(
child: Text("hello"),
onPressed: () {
var a = FirebaseAuth.instance.signInAnonymously();
print(a);
},
),
RaisedButton(
child: Text("Log out"),
onPressed: () {
var a = FirebaseAuth.instance.signOut();
print(a);
},
)
],
),