Changing theme using GetX

Question

I want to change the theme to redTheme only when I'm on a specific route. For that purpose, I've used routingCallback like

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return GetMaterialApp(
      title: 'App',
      theme: defaultTheme(context),
      initialRoute: AppPages.INITIAL,
      getPages: AppPages.routes,
      routingCallback: (routing) => _routingCallback(context, routing),
    );
  }

  _routingCallback(BuildContext context, Routing routing) {
    if (routing.current == Routes.PURSUE_MODE) {
      _changeThemeIfNeeded(redTheme(context));
    } else {
      _changeThemeIfNeeded(defaultTheme(context));
    }
  }

  void _changeThemeIfNeeded(ThemeData theme) {
    Get.changeTheme(theme);
  }
}

Unfortunately, it's causing

════════ Exception caught by widgets library ═══════════════════════════════════════════════════════ setState() or markNeedsBuild() called during build. The relevant error-causing widget was: Directionality file:///Users/jakub/.pub-cache/hosted/pub.dartlang.org/get_navigation-3.12.0/lib/src/root/root_widget.dart:235:22 ════════════════════════════════════════════════════════════════════════════════════════════════════

Because of that, I've wrapped theme changing in try-catch block, so I'm not getting exception at the start

  void _changeThemeIfNeeded(ThemeData theme) {
    try {
      if (Get.theme != theme) {
        Get.changeTheme(theme);
      }
    } catch (e) {
      print('Not ready e = $e');
    }
  }

But I believe there is more elegant approach to this problem using Get framework?

score 3 · Accepted Answer · answered Oct 06 '20 at 09:19

I'm not really familiar with GetX. However, in order to avoid setState() or markNeedsBuild() called during build. error, you can use addPostFrameCallback, in your case, like this:

routingCallback: (routing) => WidgetsBinding.instance
      .addPostFrameCallback((_) => _routingCallback(context, routing))

Changing theme using GetX

1 Answers1