Loop build widget

Question

The widget update state in build method at first. Because Riverpod rebuild the widget when update state, the widget repeat the rebuild many times. I ran into a similar problem when using Provider, but I solved it by making sure the values ​​weren't the same before doing notifyListeners() method.

Problem:

class MyWidget extends StatelessWidget {
  const WidgetC({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final state = Provider.of<HomePageState>(context, listen: true);

    return Text(state.value);
  }
}


class MyWidgetState extends ChangeNotifier {
  String value = "";

  void update() {
    // update value from Database.
    value = getValue();
    notifyListeners();
  }
}

build->update->notifyListeners->rebuild->update->notifyListeners->rebuild...

Solve:

class MyWidget extends StatelessWidget {
  const WidgetC({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    final state = Provider.of<HomePageState>(context, listen: true);

    return Text(state.value);
  }
}


class MyWidgetState extends ChangeNotifier {
  String value = "";

  void update() {
    // update value from Database.
    newValue = getValue();
    if(value != newValue) {
    notifyListeners();
    }
  }
}

build->update->notifyListeners->rebuild->update->finish(same value) or rebuild(diff value)

But, I can't solve this problem with Riverpod because value is so complicated　object class. (I try check hasCode but I can't solve).

Plz help me.

Thank you.

Answer 1

You need to warp you update with SetState() that your wirdget rebuilds

 void update() {

setState(() {
     newValue = getValue();
        if(value != newValue) {
        notifyListeners();
        });
        }
       }