Your Second Flutter App

Nov 30 2021 Dart 2.13, Flutter 2.2.3, Visual Studio Code

Part 5: Meet Inherited Widgets

34. Lift State Up

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Previous episode: 33. Create an Inherited Widget Next episode: 35. Use Portrait Mode

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This video Lift State Up was last updated on Nov 30 2021

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At the moment, the CoursesPage and FilterPage each separately maintain the state of the filter in the app. Now that you have an InheritedWidget in FilterStateContainer, you can replace the separate state on the two pages with the single state that is lifted up in the widget tree. In Flutter, this is referred to lifting state up.

late FilterState state;
import '../../state/filter_state_container.dart';
groupValue: state.filterValue,
  void _handleRadioValueChange(int value) async {
    state.updateFilterValue(value ?? 0);
  }
remove import
class _FilterPageState extends State<FilterPage> {
  late FilterState state;

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    state = FilterStateContainer.of(context);
  }
late FilterState state;
import '../../state/filter_state_container.dart';
future: _controller.fetchCourses(state.filterValue),
final courses = snapshot.data;
if (courses == null ||
              (snapshot.connectionState != ConnectionState.done)) {
  final _controller = CoursesController(CourseRepository());

  @override
  void didChangeDependencies() {
    super.didChangeDependencies();
    state = FilterStateContainer.of(context);
  }
void main() => runApp(
      FilterStateContainer(
        child: MaterialApp(
          title: Strings.appTitle,
          theme: ThemeData(primaryColor: Colors.green.shade800),
          home: const RWCoursesApp(),
        ),
      ),
    );