1. Problem description
My goal is to build a Flutter app that gets periodic location updates using this workmanager plugin and using this location plugin. But I can't get the Location plugin to be loaded properly when my Workmanager callback fires. I get this error:
MissingPluginException(No implementation found for method getLocation on channel lyokone/location)
So basically, the problem is that when the Workmanager plugin tries to run dart code, it doesn't load up the Location plugin.
2. Other resources I have researched
I found others facing the same issue, here, here, and here.
As far as I understand, the solution provided to these questions boils down to: create a file named CustomApplication.java, which extends FlutterApplication, and which registers your plugin(s). And then register the CustomApplication.java file inside you AndoidManifest.xml file.
3. My code thus far
I have tried to make a bare-minimum app that implements the features I require:
- I implemented Workmanager plugin (works fine)
- I implemented Location plugin (works fine)
- I attempted to combine these features (does not work)
To see exactly what I have done at each step, please look here: https://gitlab.com/tomoerlemans/workmanager_with_location/-/commits/master. (This repository can also be used to quickly replicate the issue).
The relevant code files are as follows:
main.dart
import 'package:flutter/material.dart';
import 'package:workmanager/workmanager.dart';
import 'package:location/location.dart';
void main() {
WidgetsFlutterBinding.ensureInitialized();
Workmanager.initialize(callbackDispatcher, isInDebugMode: true);
runApp(MyApp());
}
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: MyHomePage(),
);
}
}
class MyHomePage extends StatefulWidget {
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
RaisedButton(
onPressed: () {
Workmanager.registerPeriodicTask(
"1", "simpleTask");
},
child: Text("Start workmanager"),
),
RaisedButton(
onPressed: () {
getLocation();
},
child: Text("Get current location"),
),
],
),
),
);
}
}
void callbackDispatcher() {
Workmanager.executeTask((task, inputData) {
print("Native called background task at ${DateTime.now().toString()}");
getLocation();
return Future.value(true);
});
}
void getLocation() async {
LocationData currentLocation;
var location = new Location();
try {
currentLocation = await location.getLocation();
} on Exception catch (e) {
print("Error obtaining location: $e");
currentLocation = null;
}
print("Location altitude: ${currentLocation.altitude}");
print("Location longitude: ${currentLocation.longitude}");
}
pubspec.yaml
name: background_location
description: A new Flutter project.
version: 1.0.0+1
environment:
sdk: ">=2.1.0 <3.0.0"
dependencies:
flutter:
sdk: flutter
cupertino_icons: ^0.1.2
workmanager: ^0.2.0
location: ^2.3.5
dev_dependencies:
flutter_test:
sdk: flutter
flutter:
uses-material-design: true
CustomApplication.java
package io.flutter.plugins;
import io.flutter.app.FlutterApplication;
import io.flutter.plugin.common.PluginRegistry;
import io.flutter.plugin.common.PluginRegistry.PluginRegistrantCallback;
import io.flutter.plugins.GeneratedPluginRegistrant;
import be.tramckrijte.workmanager.WorkmanagerPlugin;
import com.lyokone.location.LocationPlugin;
public class CustomApplication extends FlutterApplication implements PluginRegistry.PluginRegistrantCallback {
@Override
public void onCreate() {
super.onCreate();
WorkmanagerPlugin.setPluginRegistrantCallback(this);
}
@Override
public void registerWith(PluginRegistry registry) {
WorkmanagerPlugin.registerWith(registry.registrarFor("be.tramckrijte.workmanager.WorkmanagerPlugin"));
LocationPlugin.registerWith(registry.registrarFor("com.lyokone.location.LocationPlugin"));
}
}
AndroidManifest.xml
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.background_location">
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
<application
android:name="io.flutter.plugins.CustomApplication"
android:label="background_location"
android:icon="@mipmap/ic_launcher">
<activity
android:name=".MainActivity"
android:launchMode="singleTop"
android:theme="@style/LaunchTheme"
android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
android:hardwareAccelerated="true"
android:windowSoftInputMode="adjustResize">
<intent-filter>
<action android:name="android.intent.action.MAIN"/>
<category android:name="android.intent.category.LAUNCHER"/>
</intent-filter>
</activity>
<meta-data
android:name="flutterEmbedding"
android:value="2" />
</application>
</manifest>
Finally, I am running the following versions of Dart/Flutter/etc:
Flutter 1.12.13+hotfix.5 • channel stable • https://github.com/flutter/flutter.git
Framework • revision 27321ebbad (10 weeks ago) • 2019-12-10 18:15:01 -0800
Engine • revision 2994f7e1e6
Tools • Dart 2.7.0