Http Network call is not working (Flutter Android)

[VarmaTech]

Hi ,

I am using workmanager for syncing data from server using http plugin in flutter android . but nothing is happening when http is called . below i am attaching my sample for code for reference

Sample Code :

import 'dart:io';

import 'package:workmanager/workmanager.dart';
import 'package:http/http.dart' as http;

const httpSync = "httpSync";
demoBackgroundSync() {
  Workmanager.initialize(startJobs, isInDebugMode: false);
  Workmanager.registerOneOffTask("3", httpSync,
      initialDelay: Duration(seconds: 5),
      constraints: Constraints(
          networkType: NetworkType.connected,
          requiresBatteryNotLow: true,
          // requiresCharging: true,
          // requiresDeviceIdle: true,
          requiresStorageNotLow: true));
}

startJobs() {
  Workmanager.executeTask((task, inputData) {
    switch (task) {
      case httpSync:
        httpSyncApis();
        break;
    }
    print(
        "Native called background task: $task"); //simpleTask will be emitted here.
    return Future.value(true);
  });
}
Map<String, String> requestHeaders = {
        HttpHeaders.contentTypeHeader: 'application/json',
        HttpHeaders.acceptHeader: 'application/json',
        // "Access-Control-Allow-Origin": "*",
        // "Access-Control-Allow-Methods": "POST,GET,DELETE,PUT,OPTIONS"
        //  'Authorization': '<Your token>'
      };
void httpSyncApis() async{

    print('Api Request  : Started');
// till here code works but after this step nothing happening 
  var response = await http
          .get(
            'http://dummy.restapiexample.com/api/v1/employees',
            headers: requestHeaders,
          )
          .timeout(const Duration(seconds: 300));
    
    print('Response Code : ${response.statusCode}');
    print('Response Body : ${response.body}');
}

console logs :

D/HostConnection(24188): HostConnection::get() New Host Connection established 0xbaf2a4a0, tid 24365
D/HostConnection(24188): HostComposition ext ANDROID_EMU_CHECKSUM_HELPER_v1 ANDROID_EMU_native_sync_v2 ANDROID_EMU_native_sync_v3 ANDROID_EMU_native_sync_v4 ANDROID_EMU_dma_v1 ANDROID_EMU_direct_mem ANDROID_EMU_host_composition_v1 ANDROID_EMU_host_composition_v2 ANDROID_EMU_YUV420_888_to_NV21 ANDROID_EMU_YUV_Cache ANDROID_EMU_async_unmap_buffer GL_OES_EGL_image_external_essl3 GL_OES_vertex_array_object GL_KHR_texture_compression_astc_ldr ANDROID_EMU_gles_max_version_3_0
D/EGL_emulation(24188): eglMakeCurrent: 0xd5e1b4a0: ver 3 0 (tinfo 0xe9589cf0)
I/flutter (24188): Api Request  : Started
I/flutter (24188): Native called background task: httpSync
I/WM-WorkerWrapper(24188): Worker result SUCCESS for Work [ id=740eaba7-dc42-4a24-b6a4-906c1218d13c, tags={ be.tramckrijte.workmanager.BackgroundWorker } ]

[abuzar-rasool]

I am having the same issue.

[Lukitaduarte]

Me too, any ideia?

[gebsl]

Can you try changing function startJobs to this:

startJobs() {
  Workmanager.executeTask((task, inputData) async {
    switch (task) {
      case httpSync:
        await httpSyncApis();
        break;
    }
    print(
        "Native called background task: $task"); //simpleTask will be emitted here.
    return true;
  });
}

Please note the added async and await keywords, as well as the changed return value.

This way, a future (not completed) is returned which will only complete after awaiting httpSyncApis to finish.

My guess why yours is not working:

You are returning an already completed future. This might tell the system your task has finished successfully, therefore not executing further code. As your http call is async, it might be dropped by the system.

[trighomautumnatg]

I am having the same issue.

[trighomautumnatg]

Can you try changing function startJobs to this:

startJobs() {
  Workmanager.executeTask((task, inputData) async {
    switch (task) {
      case httpSync:
        await httpSyncApis();
        break;
    }
    print(
        "Native called background task: $task"); //simpleTask will be emitted here.
    return true;
  });
}

Please note the added async and await keywords, as well as the changed return value.

This way, a future (not completed) is returned which will only complete after awaiting httpSyncApis to finish.

My guess why yours is not working:

You are returning an already completed future. This might tell the system your task has finished successfully, therefore not executing further code. As your http call is async, it might be dropped by the system.

It does not work

[gebsl]

@trighomautumnatg: Can you post parts of your code? Without it's difficult to tell what's wrong.

[yekkaplan]

this solution is not worked

Can you try changing function startJobs to this:

startJobs() {
  Workmanager.executeTask((task, inputData) async {
    switch (task) {
      case httpSync:
        await httpSyncApis();
        break;
    }
    print(
        "Native called background task: $task"); //simpleTask will be emitted here.
    return true;
  });
}

Please note the added async and await keywords, as well as the changed return value.

This way, a future (not completed) is returned which will only complete after awaiting httpSyncApis to finish.

My guess why yours is not working:

You are returning an already completed future. This might tell the system your task has finished successfully, therefore not executing further code. As your http call is async, it might be dropped by the system.

[gebsl]

@yekkaplan: Same here, can you post your code?

[mustafaynk]

I have some issue. This is my code;

void callbackDispatcher() { Workmanager.executeTask((taskName, inputData) async { switch (taskName) { case myTask: print('Alarm Control 1'); keysControls().then((value) async { print('Alarm Control 2'); if (value) { print('Alarm Control 3'); await getDataFromApi(); } }); break; } return Future.value(true); }); }

I can see in the console: "Alarm Control 1 - Alarm Control 2 - Alarm Control 3" but, getDataFromApi() doesn't fetch data. Actually, it doesn't request.

[gebsl]

@mustafaynk

First of all, please format you code. It's incredibly hard to read it like this.

Try this:

void callbackDispatcher() async {
  Workmanager.executeTask((taskName, inputData) async {
    switch (taskName) {
      case myTask:
        print('Alarm Control 1');

        await keysControls();
        print('Alarm Control 2');

        if (value) {
          print('Alarm Control 3');
          await getDataFromApi();
        }

        break;
    }
    return Future.value(true);
  });
}

Using async and await makes your code a lot more readable and should do what you want to achieve.

Why yours is not working? You are not awaiting the Future returned by method call keysControls, therefore the inner await getDataFromApi(); won't do anything, as the task is cancelled before the the data is fetched.

Hope this helps.

[mustafaynk]

@gebsl Sorry for bad code format because, I wrote first comment in GitHub. Actually, my problem is very obvious. My app request only one http request. I want to run http request method when app destroy. If you can help me, I will be very happy. Thanks for your reply. Have a good day.

[gebsl]

Hi @mustafaynk: You could try to combine this (https://flutter.dev/docs/get-started/flutter-for/android-devs#how-do-i-listen-to-android-activity-lifecycle-events) with flutter_workmanager.

Just run Workmanager.executeTask when the app is suspending and this should enable you to run your http call in the background.

[mustafaynk]

Hi again @gebsl ; I solved my problem. Thanks a lot.

[gebsl]

Hi @mustafaynk, can you state how you were able to solve the problem? Might also be interesting for other devs. Thanks!

[mustafaynk]

@gebsl Sure.
I called WorkManager initialize methods in initState(). WorkManager didn't work. After that, I called these methods in the 'main' method, work manager worked. Of course, I also used your advices.

[DeepaPradeepa]

Calldispatcher function does not called . Can you help me out

[DeepaPradeepa]

void callbackDispatcher() async {
Workmanager.executeTask((taskName, inputData) async {
switch (taskName) {
case fetchBackground:
print("backgroundfetchcalled in Android");
getcurrentlocation();
break;
case Workmanager.iOSBackgroundTask:
print("backgroundfetchcalled in ios");
break;
}
return true;
});

[gebsl]

Sorry, more code needed. And please format your code, it's hard to read like this.

[DeepaPradeepa]

@gebsl Please let me know how to format my code like yours

[DeepaPradeepa]

@gebsl Sure.
I called WorkManager initialize methods in initState(). WorkManager didn't work. After that, I called these methods in the 'main' method, work manager worked. Of course, I also used your advices.

Hi @mustafaynk . Can you share your worked code.

[gebsl]

@DeepaPradeepa please markup your code like this:

```dart
var x = 'yourcodegoeshere'
```

will then look like

var x = 'yourcodegoeshere'

[DeepaPradeepa]

void callbackDispatcher() async {
Workmanager.executeTask((taskName, inputData) async {
switch (taskName) {
case fetchBackground:
print("backgroundfetchcalled in Android");
getcurrentlocation();
break;
case Workmanager.iOSBackgroundTask:
print("backgroundfetchcalled in ios");
break;
}
return true;
});
}
void getcurrentlocation() async {
print("userLocationlatcalled");

try {

 // Position userLocation =  await Geolocator().getCurrentPosition(
 //     locationPermissionLevel: GeolocationPermission.location,desiredAccuracy:LocationAccuracy.high);
  print("userLocationcalled}");
 AppPreferences _appPreference;
 _appPreference = App().getAppPreferences();
 final prefs = await _appPreference.getAuthToken();
 // String tokenVal;
 LatLng userLocation = LatLng(9.98,78.11);
 //);
 await updateCurrentLoc1(userLocation,prefs);
} catch (e) {
print('Location not shared');
}
//Position userLocation = await Geolocator().getCurrentPosition(desiredAccuracy:LocationAccuracy.high);

}
Future updateCurrentLoc1(LatLng position,String token) async {
FlutterLocalNotificationsPlugin flutterLocalNotificationsPlugin =
new FlutterLocalNotificationsPlugin();
var android = new AndroidNotificationDetails(
'1', 'location-bg', 'fetch location in background',
playSound: false, importance: Importance.Max, priority: Priority.High);
var iOS = new IOSNotificationDetails();
var platform = new NotificationDetails(android, iOS);

await flutterLocalNotificationsPlugin.show(
0, "locationtop", "${position.longitude}", platform);

GraphQLClient graphQLClientWithHeader;
HttpLink httpLink =
HttpLink(uri:"GraphQLEndPoint",
headers: <String, String>{
'auth':token,
},);
graphQLClientWithHeader = GraphQLClient(
cache: new InMemoryCache(),
link: httpLink ,
);
//print("authtoken: ${globals.authToken}");

var variables = <String, dynamic>{
"lat": position.latitude,
"lng": position.longitude
};

Map<String, dynamic> _login_result = await getMutationValues(
graphQLClientWithHeader,
"updateDriverLocation_mutation",
variables);

if (_login_result["updateDriverLocation"]["status"] == 200) {
print("location updated");

await flutterLocalNotificationsPlugin.show(
    0, "locationbottom", "${position.latitude}", platform);
//sendDriverLocation1();
return "";
} else if (_login_result["updateDriverLocation"]["status"] == 500) {
print("location notupdated");
await flutterLocalNotificationsPlugin.show(
0, "locationerror", "${_login_result["updateDriverLocation"]["errorMessage"]}", platform);
// sendDriverLocation1();
return "timeout";
} else {
print("location notupdated reason ${_login_result["updateDriverLocation"]["errorMessage"]}");
await flutterLocalNotificationsPlugin.show(
0, "locationerror", "${_login_result["updateDriverLocation"]["errorMessage"]}", platform);
return _login_result["updateDriverLocation"]["errorMessage"];
}
}

          void initState() {
// getcurrentlocation();

Workmanager.initialize(
    callbackDispatcher,
    isInDebugMode:true
);

Workmanager.registerPeriodicTask(
  "1",
  fetchBackground,
  frequency: Duration(seconds:30),
);
           }

[gebsl]

First of all, a frequency of 30 seconds is not supported. The minimum time between two background calls is always 15 minutes (on Android). On iOS, you can not control the frequency at all (due to platform restrictions).

Secondly, put an await before your function call to getcurrentlocation, as otherwise callbackDispatcher will exit before running the asynchronous call.

[DeepaPradeepa]

@gebsl Yes I know that time interval which is defaultly taken as 15 mins. I tried with await callbackDispatcher as well. But I am getting failure status background fetch Pushnotification

[gebsl]

@DeepaPradeepa, have you already tried the example project to verify whether this one works or not?

[DeepaPradeepa]

@gebsl Yes. I tried with local push notification which is worked fine. But Now API Call functionality does not work

[gebsl]

I just realize we are probably not talking about the same thing.

@gebsl Yes I know that time interval which is defaultly taken as 15 mins. I tried with await callbackDispatcher as well. But I am getting failure status background fetch Pushnotification

I proposed awaiting getcurrentlocation, but you wrote you awaited callbackDispatcher. That could be the problem.

[DeepaPradeepa]

I just realize we are probably not talking about the same thing.

@gebsl Yes I know that time interval which is defaultly taken as 15 mins. I tried with await callbackDispatcher as well. But I am getting failure status background fetch Pushnotification

I proposed awaiting getcurrentlocation, but you wrote you awaited callbackDispatcher. That could be the problem.

Sorry @gebsl I wrongly told await callbackDispatcher . I have tried with await getcurrentlocation() . Same thing happened. Now I tried with native iOS Callback with Flutter. Thank you very much for helping.

[gebsl]

Oh, your issue is on iOS? I didn't know this. This whole thread is about workmanager on Android.

[Gerhardt0011]

Had the same issue, managed to resolved the issue with the following code.

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await UserSharedPrefs.init();
  Location location = new Location();
  location.enableBackgroundMode();

  Workmanager().initialize(
    callbackDispatcher,
    isInDebugMode: true,
  );

  Workmanager().registerPeriodicTask(
      "update_location_worker", "update_location_worker",
      frequency: Duration(minutes: 15),
      inputData: {
        "lat": UserSharedPrefs.getLat(),
        "long": UserSharedPrefs.getLong()
      },
      initialDelay: Duration(minutes: 1),
      constraints: Constraints(
        networkType: NetworkType.connected,
      ));
  runApp(
    OnePush(),
  );
}

Before the main() method i have this function

void callbackDispatcher() {
  Workmanager().executeTask((taskName, inputData) async {
    await UserSharedPrefs.init();
    Position position = await Geolocator.getCurrentPosition();
    UserSharedPrefs.setLat(position.latitude);
    UserSharedPrefs.setLong(position.longitude);

    final String url = 'https://72b7-154-70-228-141.ngrok.io';
    final String path = 'api/lat_long_store';

    var bearerToken = UserSharedPrefs.getBearerToken();

    var headers = {
      'Content-Type': 'application/json',
      'Accept': 'application/json',
      'Authorization': 'Bearer $bearerToken'
    };

    final body = {'lat': position.latitude, 'long': position.longitude};

    await http.post(
      Uri.parse(url + '/' + path),
      headers: headers,
      body: jsonEncode(body),
    );

    LocalNotification.Initializer();
    LocalNotification.ShowOneTimeNotification(DateTime.now());
    return Future.value(true);
  });
}

see screenshot attached, this is making a http post request :)

I know it returns a 500 server error, but just wanted to show that it is working :)