Async await does not wait for the output to return

Question

I am making an bungalow reservation system with spring rest back end and flutter front end. In this I want to get a list of bungalows. So I decided to make a method to get the list of bungalows in a method using HttpService class that I made to handle the rest end points, That method is getBungalows() method. Then I called this method by overriding initstate(). But the problem is that before my initstate() is completed. my build method starts. To prove this I printed two lines 'print' and 'print build' as I thought I get 'print build' first. what am I doing wrong here. Please help.

Method to retrieve data from rest back end

When this happened I first checked this method but this works fine and return the desired result.

Future<List<Bungalow>> getBungalows() async {
  Uri uri = Uri.parse('$url/bungalows/');
  http.Response response = await http.get(uri);

 if (response.statusCode == 200) {
   List<Bungalow> bungalows = List<Bungalow>.from(
      json.decode(response.body).map((x) => Bungalow.fromJson(x)));
   // print(bungalows.first.address + 'asafafasfafdfgfgarfgargafvfrvaerg');
   return bungalows;
 } else {
   throw 'Unable to retrieve data';
 }
 }

Code of the HomeScreen

 class _HomeScreenState extends State<HomeScreen> {
   HttpService httpService = HttpService();
   late List<Bungalow> bungalows;
   bool isLoggedIn = false;
   User? user;

   void getBungalows() async {
     bungalows = await httpService.getBungalows();
     print('done');
   }

  @override
  Widget build(BuildContext context) {
   if (widget.user != null) {
   isLoggedIn = true;
   user = widget.user;
   }
   print('done build');
   return Scaffold(
   backgroundColor: Colors.white,
   body: Column(
    children: [
      Text(isLoggedIn ? user!.userDetail.username : 'No login'),
      // TextButton(
      //     onPressed: () {
      //       setState(() {
      //         getBungalows();
      //         print(bungalows.first.address);
      //       });
      //     },
      //     child: Text('click'))
     ],
  ),
);
}

@override
 void initState() {
   getBungalows();
   
 }
}

Console Output

I/flutter (22248): done build
I/flutter (22248): done

the result is what I'd expect from what the code is right now. — Mariano Zorrilla, Oct 13 '21 at 13:32
@MarianoZorrilla what do i have to do to get the done printed first and then done build. — Indusara Umayanga, Oct 13 '21 at 13:34
@Selvin I initially tried putting set state in initState but it didnt work — Indusara Umayanga, Oct 13 '21 at 13:37

score 1 · Accepted Answer · answered Oct 13 '21 at 13:33

1

It is behaving correctly, initState function is not async and method getBungalows() is called in parallel. You should either use setState in getBungalows, or add a listener, or use the then keyword, or use StreamBuilder.

Check this: https://stackoverflow.com/a/54647682/305135

answered Oct 13 '21 at 13:33

AVEbrahimi

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You mean like this? – Indusara Umayanga Oct 13 '21 at 13:45
`void getBungalows() async { var list = await httpService.getBungalows(); setState(() { bungalows = list; }); }` – Indusara Umayanga Oct 13 '21 at 13:45
i tried the above method and this gives the same output – Indusara Umayanga Oct 13 '21 at 14:08
Create a DartPad and share, maybe I can help. – AVEbrahimi Oct 14 '21 at 05:23

Async await does not wait for the output to return

1 Answers1