Flutter - run a function every time the page changes - events

Question

I want to run a function every time the page changes in my Flutter application.
Ideally, I don't want to call this function in initState of every page, as sometimes people can forget to add the call in a new page.
Think of it as middleware - be basically before the page loads etc, some code needs to run.
Updated code for review
import 'package:flutter/material.dart';
import 'package:flutter_secure_storage/flutter_secure_storage.dart';
import 'package:myapp/pages/login_page.dart';
import 'package:myapp/pages/dashboard_page.dart';
import 'package:myapp/styles/constants.dart';
import 'package:myapp/services/auth_service.dart';
Future<void> main() async {
// create a auth service instance
AuthService authService = AuthService(secureStorage: FlutterSecureStorage());
bool isLoggedIn = await authService.isUserLoggedIn();
// run the app
runApp(MyApp(
isLoggedIn: isLoggedIn,
));
}
class MyApp extends StatefulWidget {
final bool isLoggedIn;
MyApp({this.isLoggedIn});
#override
_MyAppState createState() => _MyAppState();
}
class _MyAppState extends State<MyApp> with RouteAware {
final RouteObserver<PageRoute> routeObserver = RouteObserver<PageRoute>();
#override
void didChangeDependencies() {
super.didChangeDependencies();
routeObserver.subscribe(this, ModalRoute.of(context));
}
#override
void dispose() {
routeObserver.unsubscribe(this);
super.dispose();
}
#override
void didPush() {
print('didPush');
}
#override
void didPopNext() {
print('didPopNext');
}
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'App NAME',
theme: ThemeData(
primarySwatch: Colors.green,
primaryColor: kPrimeColour,
),
home: widget.isLoggedIn == true ? DashboardPage() : LoginPage(),
navigatorObservers: [routeObserver],
);
}
}

Answer 1

You can use implementation method didChangeDependencies this function called after initState,
flutter doc :
Subclasses rarely override this method because the framework always calls build after a dependency changes. Some subclasses do override this method because they need to do some expensive work (e.g., network fetches) when their dependencies change, and that work would be too expensive to do for every build.
Link
#override
void didChangeDependencies() {
super.didChangeDependencies();
// set your stuff here
}

Answer 2

You can use inheritance
abstract class MyState<T extends StatefulWidget> extends State {
#override
void initState() {
super.initState();
//YOUR CHANGE PAGE METHOD HERE
}
}
class YellowBird extends StatefulWidget {
const YellowBird({ Key key }) : super(key: key);
#override
_YellowBirdState createState() => _YellowBirdState();
}
class _YellowBirdState extends MyState<YellowBird> {
#override
Widget build(BuildContext context) {
return Container(color: const Color(0xFFFFE306));
}
}