firebase_database 11.0.0
firebase_database: ^11.0.0 copied to clipboard
Flutter plugin for Firebase Database, a cloud-hosted NoSQL database with realtime data syncing across Android and iOS clients, and offline access.
// Copyright 2021 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:async';
import 'package:firebase_core/firebase_core.dart';
import 'package:firebase_database/firebase_database.dart';
import 'package:firebase_database/ui/firebase_animated_list.dart';
import 'package:flutter/foundation.dart' show defaultTargetPlatform, kIsWeb;
import 'package:flutter/material.dart';
import 'firebase_options.dart';
// Change to false to use live database instance.
const USE_DATABASE_EMULATOR = true;
// The port we've set the Firebase Database emulator to run on via the
// `firebase.json` configuration file.
const emulatorPort = 9000;
// Android device emulators consider localhost of the host machine as 10.0.2.2
// so let's use that if running on Android.
final emulatorHost =
(!kIsWeb && defaultTargetPlatform == TargetPlatform.android)
? '10.0.2.2'
: 'localhost';
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp(
options: DefaultFirebaseOptions.currentPlatform,
);
if (USE_DATABASE_EMULATOR) {
FirebaseDatabase.instance.useDatabaseEmulator(emulatorHost, emulatorPort);
}
runApp(
const MaterialApp(
title: 'Flutter Database Example',
home: MyHomePage(),
),
);
}
class MyHomePage extends StatefulWidget {
const MyHomePage({Key? key}) : super(key: key);
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
late DatabaseReference _counterRef;
late DatabaseReference _messagesRef;
late StreamSubscription<DatabaseEvent> _counterSubscription;
late StreamSubscription<DatabaseEvent> _messagesSubscription;
bool _anchorToBottom = false;
String _kTestKey = 'Hello';
String _kTestValue = 'world!';
FirebaseException? _error;
bool initialized = false;
@override
void initState() {
init();
super.initState();
}
Future<void> init() async {
_counterRef = FirebaseDatabase.instance.ref('counter');
final database = FirebaseDatabase.instance;
_messagesRef = database.ref('messages');
database.setLoggingEnabled(false);
if (!kIsWeb) {
database.setPersistenceEnabled(true);
database.setPersistenceCacheSizeBytes(10000000);
}
if (!kIsWeb) {
await _counterRef.keepSynced(true);
}
setState(() {
initialized = true;
});
try {
final counterSnapshot = await _counterRef.get();
print(
'Connected to directly configured database and read '
'${counterSnapshot.value}',
);
} catch (err) {
print(err);
}
_counterSubscription = _counterRef.onValue.listen(
(DatabaseEvent event) {
setState(() {
_error = null;
_counter = (event.snapshot.value ?? 0) as int;
});
},
onError: (Object o) {
final error = o as FirebaseException;
setState(() {
_error = error;
});
},
);
final messagesQuery = _messagesRef.limitToLast(10);
_messagesSubscription = messagesQuery.onChildAdded.listen(
(DatabaseEvent event) {
print('Child added: ${event.snapshot.value}');
},
onError: (Object o) {
final error = o as FirebaseException;
print('Error: ${error.code} ${error.message}');
},
);
}
@override
void dispose() {
super.dispose();
_messagesSubscription.cancel();
_counterSubscription.cancel();
}
Future<void> _increment() async {
await _counterRef.set(ServerValue.increment(1));
await _messagesRef
.push()
.set(<String, String>{_kTestKey: '$_kTestValue $_counter'});
}
Future<void> _incrementAsTransaction() async {
try {
final transactionResult = await _counterRef.runTransaction((mutableData) {
return Transaction.success((mutableData as int? ?? 0) + 1);
});
if (transactionResult.committed) {
final newMessageRef = _messagesRef.push();
await newMessageRef.set(<String, String>{
_kTestKey: '$_kTestValue ${transactionResult.snapshot.value}',
});
}
} on FirebaseException catch (e) {
print(e.message);
}
}
Future<void> _deleteMessage(DataSnapshot snapshot) async {
final messageRef = _messagesRef.child(snapshot.key!);
await messageRef.remove();
}
void _setAnchorToBottom(bool? value) {
if (value == null) {
return;
}
setState(() {
_anchorToBottom = value;
});
}
@override
Widget build(BuildContext context) {
if (!initialized) return Container();
return Scaffold(
appBar: AppBar(
title: const Text('Flutter Database Example'),
),
body: Column(
children: [
Flexible(
child: Center(
child: _error == null
? Text(
'Button tapped $_counter time${_counter == 1 ? '' : 's'}.\n\n'
'This includes all devices, ever.',
)
: Text(
'Error retrieving button tap count:\n${_error!.message}',
),
),
),
ElevatedButton(
onPressed: _incrementAsTransaction,
child: const Text('Increment as transaction'),
),
ListTile(
leading: Checkbox(
onChanged: _setAnchorToBottom,
value: _anchorToBottom,
),
title: const Text('Anchor to bottom'),
),
Flexible(
child: FirebaseAnimatedList(
key: ValueKey<bool>(_anchorToBottom),
query: _messagesRef,
reverse: _anchorToBottom,
itemBuilder: (context, snapshot, animation, index) {
return SizeTransition(
sizeFactor: animation,
child: ListTile(
trailing: IconButton(
onPressed: () => _deleteMessage(snapshot),
icon: const Icon(Icons.delete),
),
title: Text('$index: ${snapshot.value}'),
),
);
},
),
),
],
),
floatingActionButton: FloatingActionButton(
onPressed: _increment,
tooltip: 'Increment',
child: const Icon(Icons.add),
),
);
}
}