is flutter (dart) able to make an api request in separate isolate?

Question

I made a function to post notification to a topic. It works great in normally, then I put it in compute function and hope it can posts notification in the background. But it not works. Here is my code:

void onSendMessageInBackGround(String message) {
  Future.delayed(Duration(milliseconds: 3000)).then((_) async{
    Client client = Client();
    final requestHeader = {'Authorization': 'key=my_server_key', 'Content-Type': 'application/json'};
    var data = json.encode({
      'notification': {
        'body': 'tester',
        'title': '$message',
      },
      'priority': 'high',
      'data': {
        'click_action': 'FLUTTER_NOTIFICATION_CLICK',
        'dataMessage': 'test',
        'time': "${DateTime.now()}",
      },
      'to': '/topics/uat'
    });
    await client.post('https://fcm.googleapis.com/fcm/send', headers: requestHeader, body: data);
  });
}

call compute:

compute(onSendMessageInBackGround, 'abc');

Note: I has put the onSendMessageInBackGround function at the top level of my app as the library said

Is it missing something? or we can't do that?

Answer 1

You might need to add a return or await

void onSendMessageInBackGround(String message) {
  return /* await (with async above) */ Future.delayed(Duration(milliseconds: 3000)).then((_) async{

It could be that the isolate shuts down before the request is made because you're not awaiting the Future