initialize data once in initState and call the setState when data is ready causes exception

Question

Since flutter calls the build method many times in different condition, to avoid getting the data many times, I initialize the data in initState.

I want

Answer 1

I moved my code to my build method from initState and it worked

class _TestState extends State {

  Data data;
  bool dataReady = false;

  @override
  void initState() {
    super.initState();

  }

  @override
  Widget build(BuildContext context) {
    getData(context).then((Data data) async {
      setState(() {
        dataReady= true;
      });
    });
    if (dataReady) {
      return createMainContent(context);
    } else {
      return new Container();
    }
  }

}