Flutter dart async await not working as expected

Question

I am trying to check the internet connection of the mobile device. I am using below code to check the connectivity.

import 'package:flutter/material.dart';
import 'package:internet_connection_checker/internet_connection_checker.dart';

class RedirectPage extends StatelessWidget {
  final int? status;
  
  @override
  Widget build(BuildContext context) {
      bool? isDeviceConnected;
      
      () async {
        print("a");
        print(123);
        isDeviceConnected = await checkConnection();
        print(888);
      };
      
      if (isDeviceConnected != null && isDeviceConnected == false) {
        return AppNetworkConnectivityHome();
      } else{
        return HomePage();      
      }
}
}



print(isDeviceConnected); //giving null for the first time and true or false on the second time.

Future<bool?> checkConnection() async {
  bool a = false;
  a = await InternetConnectionChecker().hasConnection;
  print(a);
  return a;
}

how to force wait for the await function to complete

could you update your code and add your full class code so we can run it? — eamirho3ein
– eamirho3ein, Commented Nov 14, 2022 at 13:30
You can't call code like that in the build method. The build method can be run at least 60 times per second.. — Robert Sandberg
– Robert Sandberg, Commented Nov 14, 2022 at 13:56

Robert Sandberg · Accepted Answer · 2022-11-14 13:06:46Z

2

You'd have to await the method call. You've currently defined it as an anonymous function, so depending on where and how you execute it there will be some differences. But it will work if you instead do something like this:

Future<bool?> myMethod() async {
   return await InternetConnectionChecker().hasConnection;
}

...
print(await myMethod());

answered Nov 14, 2022 at 13:06

Robert Sandberg

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1 Comment

fazilSizzlers Over a year ago

Thanks for the response. It makes no differnce. still doing the same.

eamirho3ein · Accepted Answer · 2022-11-14 13:40:22Z

1

You can't call async function in build method, you need to use FutureBuilder like this:

return FutureBuilder<bool>(
        future: checkConnection(),
        builder: (context, snapshot) {
          switch (snapshot.connectionState) {
            case ConnectionState.waiting:
              return Text('Loading....');
            default:
              if (snapshot.hasError) {
                return Text('Error: ${snapshot.error}');
              } else {
                bool data = snapshot.data ?? true;

                if (!data) {
                    return AppNetworkConnectivityHome();
                } else{
                    return HomePage();      
                }
              }
          }
        },
      )

edited Nov 14, 2022 at 13:40

answered Nov 14, 2022 at 13:03

eamirho3ein

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