Realtime Database connection is lost when app is disconnected from WiFi and reconnected back again

[ablbol]

[REQUIRED] Environment info

12.8.0

firebase-tools:

macOs

Platform:

[REQUIRED] Test case

I have a Flutter app that is running on a real Android device with the Firebase emulator. I followed documentation to detect user presence. Here is the code from the docs:

final connectedRef = FirebaseDatabase.instance.ref(".info/connected");
connectedRef.onValue.listen((event) {
  final connected = event.snapshot.value as bool? ?? false;
  if (connected) {
    debugPrint("Connected.");
  } else {
    debugPrint("Not connected.");
  }
});

The problem starts when I disconnect the app from WiFi and then reconnect. I noticed that I lost the connection to the Realtime Database even though I was connected to WiFi. I also noticed that since I no longer have the Realtime Database connection, the document I am interested in has the right data in the app memory but not in the Realtime Database emulator.

This is how I am listening to the document that I am interested in:

    FirebaseDatabase.instance.ref('users/$uid').onValue.listen((event) {
      debugPrint('data: ${event.snapshot.value}');
    });

[REQUIRED] Steps to reproduce

See above

[REQUIRED] Expected behavior

I expect the Realtime Database connection to come back after reconnecting to WiFi.

I also noticed that when I use the following command, the app crashes even though the command is executed once.

FirebaseDatabase.instance.setPersistenceEnabled(true);

[REQUIRED] Actual behavior

See above

[ablbol]

This is the same issue as firebase/firebase-android-sdk#5510

[aalej]

Hi @ablbol, thanks for reporting this issue. I was able to reproduce the behavior you mentioned when running a Flutter app on an Android device. Similar to what is mentioned here firebase/firebase-android-sdk#5510 (comment), it seems like the issue is only reproducible when connected to the Firebase emulators.

Let me notify our engineering team about this issue. I’ll also be marking this as reproducible.

[ablbol]

Hi, any update on this issue? thanks

[5inline]

This happens when a hard refresh is triggered in debug mode as well. The only way to reconnect seems to be to stop and restart the debug session. This makes development incredibly slow and tedious.

[OsamaQureshi796]

Hello everyone.
i just discovered the solution to the problem is that when app reconnects to wifi the sdk is not in sync with connection of realtime (.info/connected) it is not writing or reading any query from realtime. so the solution it this is first goOffline and then goOnline then will re-established the connection with realtime.

await FirebaseDatabase.instance.goOffline();
await FirebaseDatabase.instance.goOnline();