CODEWITHSUNDEEP
flutter
AiHaQ
AiHaQ

Reputation: 105

how to passing data from statefulwidget to setState

I make a statefullwidget with final variable, like password. But When I need to get data from extend statefullwidget to setstate it show error

class Inputtextfield extends StatefulWidget {
  const Inputtextfield({
    Key key, this.label, this.onChange, this.password = false,
  }) : super(key: key);

  final String label;
  final Function onChange;
  final bool password;

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

class _InputtextfieldState extends State<Inputtextfield> {
  
void _togglevisibility(){
    setState(() {
      widget.password =  !widget.password;
    });

}

i need to change it for Toggle, in setState Error say password can't be setter,cause it final, I try to fix error with Ctrl + . -> Make 'password' Not Final and error move to extend statefullWidget

Upvotes: 1

Views: 61

Answers (3)

Blo
Blo

Reputation: 11988

final keyword prevents you to re-assign its value. It's better to keep the widget constructor variables immutable, and create a mutable variable into the State itself.
Therefore, to change your variable, you need to do as follows:

class _InputtextfieldState extends State<Inputtextfield> { 

    bool _password;

    @override
    void initState() {
        super.initState();
        _password = widget.password;
    }

    void _togglevisibility(){ 
        setState(() { 
            // now, you can modify it
            _password = !_password; 
        }); 
    }
}

You can read more on this discussion: https://groups.google.com/g/flutter-dev/c/zRnFQU3iZZs/m/JX9ei27CBwAJ?pli=1

Upvotes: 1

scheinpablo
scheinpablo

Reputation: 96

  1. Make password not final.
  2. Remove the "const" from the constructor

Upvotes: 0

Abiud Orina
Abiud Orina

Reputation: 1232

It's simple. Final variables can only be set ONCE. Once you set them they cannot be changed.

 final bool password = true; // this value cannot be changed again

In your case, if you want to update the value of password, you have to make it to be Not Final by removing the final keyword ie:

bool password = false;  // this can now be changed later using `setState()`

Upvotes: 0

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