Get.back() doesn't work from an async function

[dayofbrian]

I have a page that will perform a HTTP Post when a button is pressed. That button will call an async function to perform the actual HTTP Post which could take a second or two. When I get a success or failure back I'm attempting to navigate back to the previous page, but it doesn't do anything.

No error was reported, it just fails silently.

I found a work around, just call the Get.back() function inside the button event:
onPressed: () {saveClicked(); Get.back();},

Flutter Version:
Flutter 1.12.13+hotfix.9 • channel stable • https://github.com/flutter/flutter.git
Framework • revision f139b11009 (3 weeks ago) • 2020-03-30 13:57:30 -0700
Engine • revision af51afceb8
Tools • Dart 2.7.2

Get Version:
get: ^1.17.2

Describe on which device you found the bug:
Samsung Galaxy S8

[jonataslaw]

I have a page that will perform a HTTP Post when a button is pressed. That button will call an async function to perform the actual HTTP Post which could take a second or two. When I get a success or failure back I'm attempting to navigate back to the previous page, but it doesn't do anything.

No error was reported, it just fails silently.

I found a work around, just call the Get.back() function inside the button event:
onPressed: () {saveClicked(); Get.back();},

Flutter Version:
Flutter 1.12.13+hotfix.9 • channel stable • https://github.com/flutter/flutter.git
Framework • revision f139b11009 (3 weeks ago) • 2020-03-30 13:57:30 -0700
Engine • revision af51afceb8
Tools • Dart 2.7.2

Get Version:
get: ^1.17.2

Describe on which device you found the bug:
Samsung Galaxy S8

Can you provide a Mock of the problem reproduction code? I have 3 applications in production that after the http request is sent, the app returns to the home page, and everything is working normally.
I believe that this is not related to the asynchronous function, but Get.back() should be in a place where it is never called.

Before providing your code (you can hide the API address), just test this:
onPressed: async () {saveClicked(); Get.back();},

If everything works normally, it means that there are no problems with asynchronous operations, but Get is not being called by your code.

Put a:

print("before get");
Get.back();
print("after get");

And you will know exactly what is going on. If the first print is not called, it is because your code is not even entering there.

[dayofbrian]

It was certainly being called, I had a break point on the Get.back() command and it was being hit.

I tried modifying the onPressed: to be async like you mentioned and Get.back() worked.
I did some more debugging and Get.back() only fails after I perform an await on my HTTP Post request.
I also added the print statements, and I get them both, but the page doesn't go back.

I'll try to get a minimal version together to reproduce it.

Thanks

[jonataslaw]

I tried anyway, I couldn't reproduce the error. He is apparently working properly.

void main() {
  runApp(MaterialApp(
    title: 'Test async call',
    navigatorKey: Get.key,
    home: TestScreen(),
  ));
}

class API {
  static Future<dynamic> getTestError() async {
    final response = await Dio().get('https://www.google.com');
    if (response.statusCode == 200) {
      print(response);
      Get.back();
      return response;
    } else {
      // Now you can made this
      print('error on API');
      Get.back();
    }
  }
}

class TestScreen extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Container(
          child: FlatButton(
            color: Colors.blue,
            child: Text('go to nextroute'),
            onPressed: () {
              Get.to(TestScreenTwo());
            },
          ),
        ),
      ),
    );
  }
}

class TestScreenTwo extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: Container(
          child: FlatButton(
            color: Colors.red,
            child: Text('call api'),
            onPressed: () {
              API.getTestError();
            },
          ),
        ),
      ),
    );
  }
}

[dayofbrian]

Okay, I've replicated the issue using a minor change to your sample code, it took me a while to figure out. If you put a Get.snackbar just before your Dio().get call it doesn't go back.

class API {
  static Future<dynamic> getTestError() async {
    Get.snackbar("title", "message");
    final response = await Dio().get('https://www.google.com');
    if (response.statusCode == 200) {
      print(response);
      Get.back();
      return response;
    } else {
      // Now you can made this
      print('error on API');
      Get.back();
    }
  }
}

[jlubeck]

Well, wouldn't the Get.back close the Snackbar in that situation?

[jonataslaw]

class API {
static Future getTestError() async {
Get.snackbar("title", "message");
final response = await Dio().get('https://www.google.com');
if (response.statusCode == 200) {
print(response);
Get.back();
return response;
} else {
// Now you can made this
print('error on API');
Get.back();
}
}
}

This behavior is expected, Get allows you to close a snackbar, dialog or bottomsheet dynamically, from anywhere.
If any of these are open, they will be closed, so you would need another Get.back(); to close, right?
Ideally, you should control when a dialog, snackbar or bottomsheet is open. If you can't control this, you should create some logic like this:

if(Get.isSnackbarOpen || Get.isDialogOpen || Get.isBottomsheetOpen){
Get.close(2);
} else {
Get.back();
}

Or maybe (much safer - recommended)

if(Get.isSnackbarOpen || Get.isDialogOpen || Get.isBottomsheetOpen){
navigator.popUntil((route) {
      return (!Get.isSnackbarOpen && !Get.isDialogOpen && !Get.isBottomsheetOpen);
});
}
Get.back();

Remembering that you need to add GetObserver to your MaterialApp to gain access to these features.

[dayofbrian]

Okay, that wasn't clear in your documentation. It just states 'To return to previous screen'.

Thanks for the clarification.