In Flutter, how do I pass data into a Stateless Widget?

Question

I'm trying to build my first Flutter app, and have run into difficulty with passing data into Stateless Widgets. I have the following classes:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'App Title',
      theme: new ThemeData(
        primarySwatch: Colors.green,
      ),
      home: new MainBody(),
    );
  }
}


class MainBody extends StatelessWidget {

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Padding(
        padding: const EdgeInsets.only(left: 20.0, right: 20.0),
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new TimeCheck(),
          ],
        ),
      ),
    );
  }
}

TimeCheck is a Stateful Widget. Basically, I want to be able to set some values at the start, and then pass them along to TimeCheck, via MainBody. Everything I read shows how to pass data into Stateful Widgets, but is it possible to pass it through a Stateless Widget?

I recognise I may be taking the wrong approach, so in case it helps, what I'd ultimately like to do is have a "settings" page where the user can set the values for the data (a string and some numbers), and then those values get passed to TimeCheck where they're used to generate the display.

I'd also like to be able to save the user-set values if possible, so they don't have to enter them each time, and then I'd like to be able to read them in when TimeCheck is instantiated.

score 85 · Accepted Answer · answered Sep 20 '19 at 15:52

Yes you can do this simply by passing the info to the constructor. Something like this:

 class MyApp extends StatelessWidget {
  MyApp(this.yourData);

  final int yourData;
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'App Title',
      theme: new ThemeData(
        primarySwatch: Colors.green,
      ),
      home: new MainBody(yourData),
    );
  }
}


class MainBody extends StatelessWidget {
  MainBody(this.yourData);

  final int yourData;

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      body: new Padding(
        padding: const EdgeInsets.only(left: 20.0, right: 20.0),
        child: new Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            new TimeCheck(yourData),
          ],
        ),
      ),
    );
  }
}

How can I pass that 'yourData' variable to the padding value in place of 20.0? Dart says it is not a constant. — Taha Ali, Jan 08 '20 at 12:42

score 8 · Answer 2 · edited Apr 24 '22 at 06:51

class MainMenuCard extends StatelessWidget {
final Choice choice;
final int index;

const MainMenuCard({Key key, this.choice, this.index, Choice Choice, int int})
  : super(key: key);

And Call like this

MainMenuCard(choice : choices[index],int: index)

there 'Choice' is Model class (when we using with List.generate) otherwise you can easily pass Data.

 final Choice choice;
 const List<Choice> choices = const <Choice>[]

In Flutter, how do I pass data into a Stateless Widget?

2 Answers2

Linked