How can I rerend data from Stream in Stateless Widget? - flutter

Question

I am trying to re-rend Stateless widget every time when I am getting new data from Stream. But it does not work, and I can't understand when I should to call re-rend function:
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
Stream<int> stream; // I maked it's global for simplification
void main()
{
MyClass myClass = MyClass();
WidgetsFlutterBinding.ensureInitialized();
SystemChrome.setPreferredOrientations([DeviceOrientation.landscapeLeft])
.then((_) {
runApp(new MyApp());
});
}
class MyClass
{
MyClass()
{
stream = Stream<int>.periodic(Duration(seconds: 1), (t) => t+1).take(9);
print("hello");
}
}
class MyApp extends StatelessWidget
{
#override
Widget build(BuildContext context)
{
return MaterialApp(
title: "Hello",
routes: {
'/' : (context) => SplashScreen(),
}
);
}
}
class SplashScreen extends StatelessWidget {
#override
Widget build(BuildContext context)
{
return Scaffold(
appBar: AppBar(),
body: Container(
child: Text("Hello World, $stream"),
),
);
}
}

Answer 1

please check example below
Both Parent and Child Widget are Stateless.
Use simple class to wrap stream controller, here class name is bloc
Child widget use StreamBuider
In parent widget call bloc function and pass parameter and then child widget will render
code snippet
bloc.changeState(true)
...
class Bloc {
final _fileController = StreamController<bool>();
changeState(bool val) {
_fileController.sink.add(val);
}
get hasFile => _fileController.stream;
dispose() {
_fileController.close();
}
}
full code
import 'package:flutter/material.dart';
import 'dart:async';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Homepage(),
);
}
}
class Homepage extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
actions: <Widget>[
FlatButton(
child: Text('addFile'),
onPressed: () {
bloc.changeState(true);
}),
FlatButton(
child: Text('deleteFile'),
onPressed: () {
bloc.changeState(false);
})
],
),
body: Child(),
);
}
}
class Child extends StatelessWidget {
#override
Widget build(BuildContext context) {
return StreamBuilder(
stream: bloc.hasFile,
initialData: false,
builder: (context, snapshot) {
return snapshot.data ? Text('has a file') : Text("no File");
},
);
}
}
class Bloc {
final _fileController = StreamController<bool>();
changeState(bool val) {
_fileController.sink.add(val);
}
get hasFile => _fileController.stream;
dispose() {
_fileController.close();
}
}
final bloc = Bloc();