Flutter setState causes infinite loop-CodePudding

I am newbie at Flutter, I want to fetch data once from Firebase but when I use foreach in setState, it gives infinite loop. I tried initState but I couldn't figure it out with Future.

Here is my code:

class _AnasayfaScreenState extends State<AnasayfaScreen> {
   final databaseRef = FirebaseDatabase.instance.reference();
   ActivityModel activity = ActivityModel();
   List<Map<dynamic, dynamic>> lists = [];
 }

Future getActivity() async {
return await databaseRef
    .child('activities')
    .limitToLast(3)
    .once()
    .then((DataSnapshot dataSnapshot) {
  setState(() {
    Map<dynamic, dynamic> values = dataSnapshot.value;
    lists.clear();
    values.forEach((key, values) {
      lists.add(values);
    });
  });
});
}
@override
Widget build(BuildContext context) {
getActivity();
return Scaffold(
    appBar: AppBar(
    // some stuff
  title: Text("Title: "  lists[index]["title"]  "\nDate: "   lists[index]["date"]  "\nN:  Number of people" lists[index]["maxPeople"]   "\nActivity Owner: "  lists[index]["ownername"]),

Any help would be awesome for me, thanks.

CodePudding user response：

Here is a very basic example of what you can do:


class _AnasayfaScreenState extends State<AnasayfaScreen> {
   final databaseRef = FirebaseDatabase.instance.reference();
   ActivityModel activity = ActivityModel();
  bool isLoading = true;
  List<Map<dynamic, dynamic>> lists = [];
  
  @override
  void initState(){
    super.initState();
    getActivity();
  }
  
  Future getActivity() async {
    await databaseRef
    .child('activities')
    .limitToLast(3)
    .once()
    .then((DataSnapshot dataSnapshot) {
    Map<dynamic, dynamic> values = dataSnapshot.value;
    lists.clear();
    values.forEach((key, values) {
      lists.add(values);
        });
      });
    setState(() {
      isLoading = false;
    });
  }


  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: isLoading ? Container() // Add your widget and work here instead of Container
            : CircularProgressIndicator(),
    );  
  }