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[google_maps_flutter] Fixes exception when dispose is called while asynchronous update from didUpdateWidget is executed
This PR fixes an exception in Google Maps Flutter which occurs when dispose is called while asynchronous code is executed from didUpdateWidget.
https://github.com/flutter/flutter/issues/43785
I've done the work in 2 commits, the first one just used mount checks on after each awaited retrieval of the controller. The second reuses the controller to limit the number of awaited async calls. I am a little unsure of the expected execution order of all the unawaited futures which update the controller in regards to whether dispose could still be called in between their executions. Testing locally I haven't been able to reproduce the exception with a single awaited controller.
I bumped the version 2.12.2 as no feature behaviour has changed. No new tests in this PR, I'm not sure that you can test this change using widget tests. Existing test coverage ensures that the values are still being updated correctly.
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- [/] I updated
pubspec.yamlwith an appropriate new version according to the pub versioning philosophy, or I have commented below to indicate which version change exemption this PR falls under[^1]. - [/] I updated
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Code Sample
This sample app can be used to trigger the error, just repeatedly tapping the button at the bottom of the screen to reload the map. I did the testing in Chrome using the google_maps_flutter_web example project and the javascript key in web/index.html
import 'package:flutter/material.dart';
import 'package:google_maps_flutter/google_maps_flutter.dart';
void main() {
runApp(const MapToggleWidget());
}
class MapToggleWidget extends StatefulWidget {
const MapToggleWidget({Key? key}) : super(key: key);
@override
_MapToggleWidgetState createState() => _MapToggleWidgetState();
}
class _MapToggleWidgetState extends State<MapToggleWidget> {
bool _showMap = true;
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(title: const Text('Map Toggle Example')),
body: Column(
children: [
Expanded(child: _showMap ? buildGoogleMap() : buildNoMapContainer()),
Padding(
padding: const EdgeInsets.all(8.0),
child: ElevatedButton(
onPressed: () => setState(() => _showMap = !_showMap),
child: Text(_showMap ? 'Hide Map' : 'Show Map'),
),
),
],
),
),
);
}
Container buildNoMapContainer() {
return Container(
color: Colors.grey[300],
child: const Center(
child: Text(
'Map is hidden',
style: TextStyle(fontSize: 18),
),
),
);
}
GoogleMap buildGoogleMap() {
return const GoogleMap(
mapType: MapType.satellite,
initialCameraPosition: CameraPosition(
target: LatLng(-38.9000, 175.8000),
zoom: 10.0,
),
);
}
}
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I'm not sure how I would go about writing a test to make sure that the call from async code is not executed if the widget state has been disposed. If it's possible would the execution of the async code being non-deterministic probably result in a flaky test.
If it's possible would the execution of the async code being non-deterministic probably result in a flaky test.
Why would it be non-deterministic in a test? onPlatformViewCreated is public, so you should be able to control when it is called (and thus when awaiting _controller resolves) relative to other methods, by calling it explicitly.
@stuartmorgan-g I've added tests covering both the didUpdateWidget and onPlatformViewCreated calls.
I have also expanded the mount check around the call to onMapCreated inside onPlatformViewCreated as it seems strange to me that you'd want to call it if the widget has been disposed. Do you agree with this or just back it off to only include the call to _updateTileOverlays?
If the mount check around onMapCreated is fine then I'll add a test for it also.
I was also wondering if there is a technical reason the tile overlays are updated only after the controller is available and not set in the initState like the rest of the state?
@tarrinneal Any update on this one? This is causing lot of noise in our bug tracking events manager. Not causing the app to crash, but still very annoying !
From triage: @JamesMcIntosh are you still planning on updating this PR based on the review feedback?
Hi @stuartmorgan-g, Sorry it's been a while, it's on my TODO list for this week. James
I receive error in the web version:
DartError: Bad state: Cannot add new events after calling close
dart-sdk/lib/internal/js_dev_runtime/private/ddc_runtime/errors.dart 288:3 throw
dart-sdk/lib/async/broadcast_stream_controller.dart 243:24 add
packages/google_maps_flutter_web/src/google_maps_controller.dart 250:7
About before comment, I tested in web version that need adaptive this code for google_maps_flutter_web to it didn't show the same error.