flutter warning Do not use BuildContexts across async gaps

Question

I'm facing a warning of Do not use BuildContexts across async gaps.

Kindly tell me what is meant by this warning and why I'm facing this warning.

I couldn't resolve this warning from few days. Please help me on solving this warning.

class CategoryService extends ChangeNotifier {
  List<Data> list = [];

  showCategory(BuildContext context) async {
    var connectivityResult = await (Connectivity().checkConnectivity());
    if (connectivityResult == ConnectivityResult.mobile ||
        connectivityResult == ConnectivityResult.wifi) {
      Utils.showLoader(context);                         // facing warning on this line
      ApiCall.getCategory().then((value) async {
        if (value.statusCode == 200) {
          if (json.decode(value.body)["success"] != null) {
            if (json.decode(value.body)["success"]) {
              CategoryModel categoryModel =
                  CategoryModel.fromJson(json.decode(value.body));
              list.clear();
              list.addAll(categoryModel.data ?? []);
              notifyListeners();
              Get.back();
              notifyListeners();
            } else {
              Utils.flushBarErrorMessage(
                  json.decode(value.body)["en_message"], context);
              Utils.hideLoader(context);
            }
          } else {
            Utils.flushBarErrorMessage(
                jsonDecode(value.body)["error"], context);
            Utils.hideLoader(context);
          }
        } else {
          Utils.flushBarErrorMessage('Invalid Data', context);
          Utils.hideLoader(context);
        }
      }).catchError((onError) {
        Utils.hideLoader(context);
        log("my Error");
        debugPrint(onError.toString());
      });
    } else {
      Utils.hideLoader(context);                        // facing warning on this line
      Utils.flushBarErrorMessage('No Internet', context);    // facing warning on this line
    }
  }
}

EDITED

I'm using my showCategory here in HomeScreen

class HomeScreen extends StatefulWidget {
  const HomeScreen({Key? key}) : super(key: key);

  @override
  State<HomeScreen> createState() => _HomeScreenState();
}

class _HomeScreenState extends State<HomeScreen> {
  late CategoryService categoryService;
  bool isCalled = false;

  @override
  Widget build(BuildContext context) {
    if (!isCalled) {
      isCalled = true;
      categoryService = Provider.of<CategoryService>(context);
      categoryService.showCategory(context);
    }
    return Scaffold(
      appBar: AppBar(
        title: const Text('Home'),
        centerTitle: true,
      ),
      body: Column(
        children: [
          const Align(
            alignment: Alignment.centerLeft,
            child: Padding(
              padding: EdgeInsets.symmetric(horizontal: 15),
              child: Text('Category'),
            ),
          ),
          const SizedBox(height: 10),
          Padding(
            padding: const EdgeInsets.symmetric(horizontal: 15),
            child: GridView.builder(
              itemCount: categoryService.list.length,
              shrinkWrap: true,
              primary: false,
              gridDelegate: const SliverGridDelegateWithFixedCrossAxisCount(
                crossAxisCount: 3,
                crossAxisSpacing: 8,
                mainAxisSpacing: 10,
              ),
              itemBuilder: (context, index) => Center(
                child: GridCategory(
                  category: categoryService.list[index],
                ),
              ),
            ),
          ),
          const SizedBox(height: 20),
        ],
      ),
    );
  }
}

Md. Yeasin Sheikh · Answer 1 · 2022-08-10T15:41:36.467

0

Check if it is mounted or not.

 if (!mounted) return;

This is not available outside the state class. You can pass state trough constructor if necessary like.

Rename the state if needed to make it public like

_HomeScreenState to HomeScreenState

Now pass state to your method in order to access mounted getter.

 showCategory(BuildContext context, HomeScreenState state) async {

  .....
  connectivityResult == ConnectivityResult.wifi) {
   if(!state.mounted) return;
  ....

Now when you use showCategory pass the state

like

 categoryService.showCategory(context, HomeScreenState);

edited Aug 10 '22 at 15:41

answered Aug 10 '22 at 08:37

Md. Yeasin Sheikh

54,221
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I've tried this already but facing `Undefined name 'mounted'.` – Aug 10 '22 at 08:39
If it is necessary you can pass the state outside the state method – Md. Yeasin Sheikh Aug 10 '22 at 08:42
How to write this ? – Aug 10 '22 at 08:46
Check update snippet – Md. Yeasin Sheikh Aug 10 '22 at 08:47
can you edit the answer how to proper write like my above question as I'm facing so many error after doing this. – Aug 10 '22 at 08:52
in which state you are using this `showCategory` – Md. Yeasin Sheikh Aug 10 '22 at 08:53
Check my edited question – Aug 10 '22 at 09:00
check update answer, you might not need to make it public, give a try – Md. Yeasin Sheikh Aug 10 '22 at 15:42
now category doesn't shown. – Aug 11 '22 at 05:54
seems like you are using after disposed, better change the async logic on state class to use context – Md. Yeasin Sheikh Aug 11 '22 at 07:13

flutter warning Do not use BuildContexts across async gaps

1 Answers1