Flutter: Error "The getter 'mydata' isn't defined for the type 'providerdemo' " eventhough I've defined them in providerdemo classs

Question

I've defined a variable myvalue for accessing the document field from cloud firestore in Provider class providerdemo .But when I am trying to access it shows error The getter 'mydata' isn't defined for the type 'providerdemo'. .What's wrong in my code ?

providerdemo.dart

class providerdemo with ChangeNotifier {
  static String? mydata;
  final userData = FirebaseFirestore.instance
      .collection("Users")
      .doc(FirebaseAuth.instance.currentUser!.uid)
      .get()
      .then((value) {
     mydata =(value.data()?['uname'] ?? "Default userName");
}

Below is the class where I'm trying to access the value into Text() widget;

class _testState extends State<test> {

  @override
  Widget build(BuildContext context) {
    return Scaffold(
     body: Text(Provider.of<providerdemo>(context).mydata ?? "default"),
    );
  }
}

Answer 1

You are getting the error The getter 'mydata' isn't defined for the type 'providerdemo' because you have not defined the function mydata in the providerdemo class

---

Further there are two problems:

1. You are defining the mydata twice, because of which it is not updating ,
2. It is not value.data() ?? ["uname"] it is value.data()["uname"] ?? "Default userName"

class providerdemo with ChangeNotifier {
  static String mydata;
  final userData = FirebaseFirestore.instance
      .collection("Users")
      .doc(FirebaseAuth.instance.currentUser!.uid)
      .get()
      .then((value) {

    // var mydata = (value.data() ?? ["uname"]); // 👈 You are creating new variable mydata
      
       mydata = (value.data()?['uname'] ?? "Default userName"); //👈 Replace the above line by this

       print(mydata)  // Print the data once so that you know if the correct data is fetched.
  });
  notifyListeners();
}

So now you can use it as Text(providerdemo.mydata)

---

Edit

Create Notifier

class UsersState extends ChangeNotifier{
String userName = '';

void getName(){
  FirebaseFirestore.instance
      .collection("Users")
      .doc(FirebaseAuth.instance.currentUser!.uid)
      .get()
      .then((value) {
         userName = (value.data()?[' uname'] ?? "Default userName");
         print(userName)  // Print the data once so that you know if the correct data is fetched.
    });
    notifyListeners();
}

Change your main.dart file to contain Notifier

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return ChangeNotifierProvider<UserState>(
      create: (context)=> UsersState(),
      child:MaterialApp(
        home: myHomePage(),
      )
    );
  }
}

Screen where you want to display the name

class ProfileScreen extends StatelessWidget {
  const ProfileScreen({super.key});

  @override
  Widget build(BuildContext context) {
    Provider.of<UserState>(context, listen: false).getName();
    final String name = Provider.of<UsersState>(context).userName;

    return Center(
      child: Text(name),
    );
  }
}