How to refresh or reload a flutter firestore streambuilder manually? - flutter

Question

I have this application that needs a pull to refresh functionality, so I placed the StreamBuilder Widget inside the RefreshIndicator Widget, but I don't know how to manually refresh the StreamBuilder when the onRefreshed event is triggered.

Answer 1

Having the stream as a state variable and resetting on pull on refresh will solve the problem.
In below code, I am resetting the stream on button press. Hope that helps you.
import 'dart:async';
import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatefulWidget {
#override
State<StatefulWidget> createState() {
return new _MyAppState();
}
}
class _MyAppState extends State<MyApp> {
var stream; // state variable
#override
void initState() {
super.initState();
stream = newStream(); // initial stream
}
Stream<String> newStream() =>
Stream.periodic(Duration(seconds: 1), (i) => "$i");
#override
Widget build(BuildContext context) {
var streamBuilder = StreamBuilder(
initialData: "0",
stream: stream,
builder: (context, snapshot) {
return new Text(snapshot.data);
});
return MaterialApp(
title: 'Trial',
home: Scaffold(
appBar: AppBar(title: Text('Stream builder')),
body: Column(
children: <Widget>[
streamBuilder,
FlatButton(
onPressed: () {
setState(() {
stream = newStream(); //refresh/reset the stream
});
},
child: Text("Reset"))
],
)));
}
}

Answer 2

Try to use this sample with rxdart package:
class _MyAppState extends State<MyApp> {
/// Controller for stream with `Object` (actually any) signal
final controller = PublishSubject<Object>();
/// Stream returning as transformed `Future` with Firebase data
Stream<List> get stream => controller.asyncMap(_onRefreshFirebase);
#override
void dispose() {
controller.close();
super.dispose();
}
#override
void initState() {
super.initState();
controller.add(Object()); // Activate stream
}
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Trial',
home: Scaffold(
appBar: AppBar(title: Text('Stream builder')),
body: Column(
children: <Widget>[
RefreshIndicator(
onRefresh: _onRefresh,
child: StreamBuilder<List>(
stream: stream,
builder: (context, snapshot) {
// use data from `snapshot`
return ListView.builder(...),
},
),
),
FlatButton(
child: Text('Reload'),
onPressed: () {
// Prepare new data and send it to stream
controller.add(Object());
}
),
],
),
);
}
}
}
/// Stream transformer from `event` to `List<dynamic>`
Future<List> _onRefreshFirebase(Object event) async {
// get data from Firebase
return [];
}
/// Callback when user pulls down
Future _onRefresh() async {
await _onRefreshFirebase(Object());
}