Flutter - display field - name - of user that is logged in - flutter

Question

Im trying to display name of user that is currently logged in app. I have this code right now but its showing me "Document does not exist". I have it from other person that was asking here on stackoverflow but they figured it somehow but didnt post the full correct code so im asking here again. Link Retrieve one field from firebase and display it in a Text Widget
class ProfilePage extends StatefulWidget {
const ProfilePage({Key? key}) : super(key: key);
#override
State<ProfilePage> createState() => _ProfilePageState();
}
class _ProfilePageState extends State<ProfilePage> {
DocumentReference userName = FirebaseFirestore.instance
.collection('users')
.doc(FirebaseAuth.instance.currentUser!.uid);
//Variable used to store the name
String name = '';
#override
void initState() {
super.initState();
userName.get().then((DocumentSnapshot ds) {
name = ds['name'];
});
}
#override
Widget build(BuildContext context) {
return SingleChildScrollView(
child: Column(
children: <Widget>[
FutureBuilder<DocumentSnapshot>(
future: userName.get(),
builder:
(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError) {
return const Text("Something went wrong");
}
if (snapshot.hasData && !snapshot.data!.exists) {
return const Text("Document does not exist");
}
if (snapshot.connectionState == ConnectionState.done) {
Map<String, dynamic> data = snapshot.data!.data() as Map<String, dynamic>;
return Text("Full Name: ${data['name']}");
}
return const Text("loading");
},
)
],
),
);
}
}

Answer 1

First make sure that "FirebaseAuth.instance.currentUser!.uid" doesn't give null and there is an internet connection.
Then, there are two ways:
Do the following function, and call it in initState method
Future<void> getUserData(String userID) async {
DocumentReference authResult =
FirebaseFirestore.instance.collection('users').doc(userID);
DocumentSnapshot docSnap = await authResult.get();
var data = docSnap.data() as Map<String, dynamic>;
name = data['name'];
}
when you call this function, pass the userId as an argument to the function
OR
Instead of implementing a function and call it in initState you can call didChangeDependencies and make it async
#override
void didChangeDependencies() async {
super.didChangeDependencies();
DocumentReference authResult =
FirebaseFirestore.instance.collection('users').doc(userID);
DocumentSnapshot docSnap = await authResult.get();
var data = docSnap.data() as Map<String, dynamic>;
name = data['name'];
}
Edit
class ProfilePage extends StatefulWidget {
const ProfilePage({Key? key}) : super(key: key);
#override
State<ProfilePage> createState() => _ProfilePageState();
}
class _ProfilePageState extends State<ProfilePage> {
DocumentReference userName = FirebaseFirestore.instance
.collection('users')
.doc(FirebaseAuth.instance.currentUser!.uid);
//Variable used to store the name
String name = '';
#override
void didChangeDependencies() async {
super.didChangeDependencies();
DocumentReference authResult =
FirebaseFirestore.instance.collection('users').doc(FirebaseAuth.instance.currentUser!.uid);
DocumentSnapshot docSnap = await authResult.get();
var data = docSnap.data() as Map<String, dynamic>;
name = data['name'];
}
#override
Widget build(BuildContext context) {
return SingleChildScrollView(
child: Column(
children: <Widget>[
FutureBuilder<DocumentSnapshot>(
future: userName.get(),
builder:
(BuildContext context, AsyncSnapshot<DocumentSnapshot> snapshot) {
if (snapshot.hasError) {
return const Text("Something went wrong");
}
if (snapshot.hasData && !snapshot.data!.exists) {
return const Text("Document does not exist");
}
if (snapshot.connectionState == ConnectionState.done) {
Map<String, dynamic> data = snapshot.data!.data() as Map<String, dynamic>;
return Text("Full Name: ${data['name']}");
}
return const Text("loading");
},
)
],
),
);
}
}