🐛 [firebase_database] Listener overwritten by .get()

[proczak1]

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Bug report

Describe the bug When i do: REFERENCE.orderByKey().startAt(...).endAt(...) to listen to changes (onAdded, onChanged, onRemoved) it is working fine, unless i make another request for the same database REFERENCE like: REFERENCE.orderByKey().startAt(...).endAt(...).get() with let's say smaller range. Then first listener show results for range from .GET()

Steps to reproduce

Steps to reproduce the behavior:

1. Start listeners (onAdded, change, removed) for REFERENCE.orderByKey().startAt(START).endAt(END)
2. Get data from database with: REFERENCE..orderByKey().startAt(START2).endAt(END2) (with smaller range than above)
3. Listeners starts showing data from START2 to END2

Expected behavior

Listener should show data from START to END

Sample project

Database items: ref/items (key, value): (1,1), (2,2), (10,10), (31, 31) onPressed: (){ Query query = FirebaseDatabase.instance.ref().child('items').orderByKey().startAt('1').endAt('31'); query.onChildAdded.listen((event) { print('added ${event.snapshot.key}'); }); FirebaseDatabase.instance.ref().child('items').orderByKey().startAt('10').endAt('20').get(); }

Console output: I/flutter ( 8219): added 10

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Additional context

Add any other context about the problem here.

---

Flutter doctor

Run flutter doctor and paste the output below:

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Doctor summary (to see all details, run flutter doctor -v):
[√] Flutter (Channel stable, 3.0.5, on Microsoft Windows [Version 10.0.22000.795], locale pl-PL)
[√] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[√] Chrome - develop for the web
[√] Visual Studio - develop for Windows (Visual Studio Community 2022 17.1.6)
[√] Android Studio (version 2020.3)
[√] Android Studio (version 2021.2)
[√] VS Code (version 1.69.2)
[√] Connected device (4 available)
[√] HTTP Host Availability

• No issues found!

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Flutter dependencies

Run flutter pub deps -- --style=compact and paste the output below:

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 firebase_auth: ^3.4.1
  firebase_analytics: ^9.1.12
  firebase_database: ^9.0.18
  firebase_messaging: ^11.4.4
  firebase_storage: ^10.3.1
  firebase_core: ^1.19.1
  google_mobile_ads: ^1.3.0
  firebase_crashlytics: ^2.8.4
  firebase_dynamic_links: ^4.3.1
  cloud_functions: ^3.3.3

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[darshankawar]

@proczak1 You didn't fill the issue template completely, so we can't properly debug the behavior you are reporting. Please provide flutter doctor -v, plugin version, a complete minimal reproducible code sample along with actual vs expected behavior.

Thanks.

[proczak1]

Sorry for that. Fixed

[darshankawar]

a complete minimal reproducible code sample along with actual vs expected behavior.

Also please provide this.

[proczak1]

Done

[darshankawar]

Thanks for the update and sorry for coming back late on this. Is this happening on mobile (android, ios specifically) or on web ? Also, if you try once() instead of get(), do you get expected behavior ?

[proczak1]

Android and iOS. Didn't test web With once result is proper

wt., 26 lip 2022, 13:51 użytkownik darshankawar @.***> napisał:

Thanks for the update and sorry for coming back late on this. Is this happening on mobile (android, ios specifically) or on web ? Also, if you try once() instead of get(), do you get expected behavior ?

— Reply to this email directly, view it on GitHub https://github.com/firebase/flutterfire/issues/9158#issuecomment-1195381990, or unsubscribe https://github.com/notifications/unsubscribe-auth/ATQCCYVAOFS6DRCKSWLEQTDVV7GK5ANCNFSM54CNUWUQ . You are receiving this because you were mentioned.Message ID: @.***>

[darshankawar]

Can you try below code sample wherein onValue listener is getting called after reading data using get() and see if using it, you see correct behavior ?

code sample

// 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: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 = false;
// 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;

  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;
        });
      },
    );

    // made changes here compared to the firebase_database example code
    final messagesQuery = _messagesRef.orderByChild(_kTestKey).limitToFirst(10);

    _messagesSubscription = messagesQuery.onValue.listen(
      (DatabaseEvent event) {
        print('onValue called : ${event.snapshot.children.length}');
      },
      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'});
  }

  @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}',
                    ),
            ),
          ),
          // made changes here compared to the firebase_database example code
          ElevatedButton(
            onPressed: () {
              print('called >>>>>> get single data');
              _messagesRef.orderByChild(_kTestKey).limitToFirst(1).get();
            },
            child: const Text('get single data'),
          ),
        ],
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _increment,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

You might need to modify this code per your case.

[proczak1]

After 10 messages i still get notified with: onValue called : 10

[darshankawar]

Thanks for the update. Using the code sample provided earlier, I see same behavior as reported, but I am not completely sure if this is expected behavior or a potential bug with how get() retrieves the data. Also, the fact that using once(), it works as expected.

May be a related issue on how get() retrieves the data, which may be related to the api itself:

https://github.com/firebase/flutterfire/issues/9067

[proczak1]

Any update on this? Once is not an option as its result is just from cache. .get() every time crushes listener. Makes no sense...

[proczak1]

It also seems like this happens ONLY if listener has both startAt and endAt

[maneesht]

Hi, I'm a maintainer on the RTDB JS SDK team and it should have been resolved in a previous version. Can you please try upgrading flutterfire?

[russellwheatley]

@proczak1 - is this still occurring on native platforms?

[google-oss-bot]

Hey @proczak1. We need more information to resolve this issue but there hasn't been an update in 7 weekdays. I'm marking the issue as stale and if there are no new updates in the next 7 days I will close it automatically.

If you have more information that will help us get to the bottom of this, just add a comment!

[google-oss-bot]

Since there haven't been any recent updates here, I am going to close this issue.

@proczak1 if you're still experiencing this problem and want to continue the discussion just leave a comment here and we are happy to re-open this.