CODEWITHSUNDEEP
flutter
Dimitri Leurs
Dimitri Leurs

Reputation: 702

Stateful widget, class marked @immutable

I got a Visual Studio warning on my class (below) saying "This class (or a class which this class inherits from) is marked as '@immutable', but one or more of its instance fields are not final: UserSignIn._email", but I cannot mark this argument as final because I initialise it in the constructor

Without final :

class UserSignIn extends StatefulWidget {
  TextEditingController _email;

  UserSignIn({String emailInput}) {
    this._email = TextEditingController(text: (emailInput ?? ""));
  }

  @override
  _UserSignInState createState() => _UserSignInState();
}

class _UserSignInState extends State<UserSignIn> {
  @override
    Widget build(BuildContext context) {
    ... 
    }
}

How to do this ?

Thank you

Upvotes: 0

Views: 1518

Answers (1)

Isti01
Isti01

Reputation: 873

You should put the TextEditingController in the state class and initialise it in the initState method, like this.

And keep in mind that the StatefulWidget can be different every time when the widget tree is changed, so don't put anything in there that is not immutable. Keep everything dynamic in the State class

class UserSignIn extends StatefulWidget {
  final String emailInput;

  const UserSignIn({Key key, this.emailInput}) : super(key: key);
  @override
  _UserSignInState createState() => _UserSignInState();
}

class _UserSignInState extends State<UserSignIn> {
  TextEditingController _controller;

  @override
  void initState() {
    _controller = TextEditingController(text: widget.emailInput);
    super.initState();
  }

...
}

Upvotes: 4

Related Questions