How to set data in an inherited widget from a another widget? - flutter

Question

So inherited widget is useful for passing data down the tree, but how do I set that data in the first place if inherited widgets are immutable?
I'm trying to set a phone number for OTP auth and then display that number on another screen. Provider is kind of advanced for me at the moment, how do I approach this?
thank you

Answer 1

You have to rebuild somewhere your InheritedWidget.
You can use any stage management for it, for example you can use StatefulWidget:
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
class MyInheritedWidget extends InheritedWidget {
final int counter;
MyInheritedWidget({Key key, this.counter, Widget child})
: super(key: key, child: child);
#override
bool updateShouldNotify(MyInheritedWidget oldWidget) {
return oldWidget.counter != counter;
}
static MyInheritedWidget of(BuildContext context) {
return context.dependOnInheritedWidgetOfExactType<MyInheritedWidget>();
}
}
void main() {
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
home: Home(),
);
}
}
class Home extends StatefulWidget {
#override
_HomeState createState() => _HomeState();
}
class _HomeState extends State<Home> {
int _counter = 0;
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: MyInheritedWidget(counter: _counter, child: CounterWidget()),
),
floatingActionButton: FloatingActionButton(
onPressed: () {
setState(() {
_counter++;
});
},
),
);
}
}
class CounterWidget extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Text("${MyInheritedWidget.of(context).counter}",
style: TextStyle(fontSize: 100));
}
}

Answer 2

Firstly you would use a StreamProvider for your stream of data (The same as you would using a StreamBuilder):
class Widget1 extends StatelessWidget {
#override
Widget build(BuildContext context) {
return StreamProvider<User>.value(
value: AuthService().user,
child: Wrapper(),
);
}
}
Next widget has no required data
class Widget2 extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Container(
child: Widget3(),
);
}
}
Access your data via Provider.of
class Widget3 extends StatelessWidget {
#override
Widget build(BuildContext context) {
final user = Provider.of<User>(context);
if (user == null) {
return Login();
} else {
return Dashboard();
}
}
}
With this method, you still need to access the data somewhere down the widget tree. You can't go up, if you want to have the ability to have a widget up the tree listen to something that happens down the tree, you will want to look at ChangeNotifier