Exclamation mark in front of await - flutter

One case I've looked up where this is used is Navigator with WillPopScope as the parent as mentioned in the comment of this answer.
To put my question concretely, the following code should pop from the nested navigator but instead the app exits when the back button is pressed on android.
void main() {
runApp(MaterialApp(title: 'Navigation Basics', home: PearlScreen()));
}
class PearlScreen extends StatefulWidget {
const PearlScreen({Key? key}) : super(key: key);
#override
State<PearlScreen> createState() => _PearlScreenState();
}
class _PearlScreenState extends State<PearlScreen> {
final _navigatorKey = GlobalKey<NavigatorState>();
#override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: () async => await _navigatorKey.currentState!.maybePop(),
child: Navigator(
key: _navigatorKey,
onGenerateRoute: (settings) {
Widget screen;
switch (settings.name) {
case '/':
screen = const HomeScreen();
break;
case '/quiz':
screen = const QuizScreen();
break;
default:
throw "Invalid route in Pearl: ${settings.name}";
}
return MaterialPageRoute(
builder: (_) => Material(child: screen),
);
},
),
);
}
}
But as soon as I change it to onWillPop: () async => !await _navigatorKey.currentState!.maybePop(), it works correctly and pops from the nested navigator instead of exiting the app.
What is the significance of !await?

Related

Flutter: Error says - Could not find a generator for route RouteSettings while trying to navigate to another screen

Although questions with such error messages exist in this site, none solves my problem.
I have a button and on clicking the button, I just need to go to a different screen. But when ever I tap on the screen, the error shows up.
I first setup a route in MaterialApp and then tried to navigate to that route on tapping the button. The full code and the error message are given below:
Code:
import 'livesession1to1.dart';
class NavigationService {
static GlobalKey<NavigatorState> navigatorKey =
GlobalKey<NavigatorState>();
}
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
runApp(MaterialApp(
home: CountDownTimer(),
navigatorKey: NavigationService.navigatorKey, // set property// Added by me later from prev project
// initialRoute: "/",
routes: <String, WidgetBuilder> {
'/liveSession1to1': (context) =>LiveSession1to1(),
},
)
);
}// end of main
class CountDownTimer extends StatefulWidget {
const CountDownTimer();
final String? title='';
#override
_CountDownTimerState createState() => _CountDownTimerState();
}
class _CountDownTimerState extends State<CountDownTimer> {
#override
void initState() {
super.initState();
}// end of initstate
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text('Live Session'),
),
body: Text('Demo Text'),
floatingActionButton: Row(
mainAxisAlignment: MainAxisAlignment.center,
children: [
_button(title: "Go", onPressed: () =>
Navigator.of(context ,rootNavigator: true).pushNamed('/liveSession1to1', arguments: {'room_found': 123 } )
),
],
),
floatingActionButtonLocation: FloatingActionButtonLocation.centerFloat,
);
}
Widget _button({required String title, VoidCallback? onPressed}) {
return Expanded(
child: TextButton(
child: Text(
title,
style: const TextStyle(color: Colors.white),
),
style: ButtonStyle(
backgroundColor: MaterialStateProperty.all(Colors.red),
),
onPressed: onPressed,
));
}
}
Error found:
The following assertion was thrown while handling a gesture:
Could not find a generator for route RouteSettings("/liveSession1to1", {room_found: 123}) in the _WidgetsAppState.
Make sure your root app widget has provided a way to generate
this route.
Generators for routes are searched for in the following order:
For the "/" route, the "home" property, if non-null, is used.
Otherwise, the "routes" table is used, if it has an entry for the route.
Otherwise, onGenerateRoute is called. It should return a non-null value for any valid route not handled by "home" and "routes".
Finally if all else fails onUnknownRoute is called.
Unfortunately, onUnknownRoute was not set.
So how to solve the problem ?
import 'package:flutter/material.dart';
import 'package:flutter/services.dart';
import 'package:get_it/get_it.dart';
void main() {
locatorSetup();
runApp(MyApp());
}
class MyApp extends StatelessWidget {
final _navService = locator<NavigationHandler>();
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
onGenerateRoute: generateRoute,
navigatorKey: _navService.navigatorKey,
// I don't know what your first screen is, so I'm assuming it's a Splash Screen
home: SplashScreen());
}
}
class SplashScreen extends StatefulWidget {
const SplashScreen({Key? key}) : super(key: key);
#override
State<SplashScreen> createState() => _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
final _navService = locator<NavigationHandler>();
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: ElevatedButton(
onPressed: () {
_navService.pushNamed(Routes.LiveSession1to1);
},
child: Text("Go to next page"),
),
));
}
}
class LiveSession1to1 extends StatefulWidget {
const LiveSession1to1({Key? key}) : super(key: key);
#override
State<LiveSession1to1> createState() => _LiveSession1to1State();
}
class _LiveSession1to1State extends State<LiveSession1to1> {
final _navService = locator<NavigationHandler>();
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: ElevatedButton(
onPressed: () {
_navService.goBack();
},
child: Text("Go to previous page"),
),
));
}
}
GetIt locator = GetIt.instance;
void locatorSetup() {
locator
.registerLazySingleton<NavigationHandler>(() => NavigationHandlerImpl());
}
Route<dynamic> generateRoute(RouteSettings settings) {
switch (settings.name) {
case Routes.LiveSession1to1:
return _getPageRoute(view: LiveSession1to1(), routeName: settings.name);
default:
return MaterialPageRoute(
builder: (_) => Scaffold(
body: Center(
child: Text('No route defined for ${settings.name}'),
),
),
);
}
}
PageRoute _getPageRoute({String? routeName, Widget? view}) {
return MaterialPageRoute(
settings: RouteSettings(
name: routeName,
),
builder: (_) => view!,
);
}
class Routes {
static const String LiveSession1to1 = "liveSession1to1";
}
abstract class NavigationHandler {
///Pushes `destinationRoute` route onto the stack
Future<dynamic>? pushNamed(String destinationRoute, {dynamic arg});
///Pushes `destinationRoute` onto stack and removes stack items until
///`lastRoute` is hit
Future<dynamic>? pushNamedAndRemoveUntil(
String destinationRoute, String lastRoute,
{dynamic arg});
///Pushes `destinationRoute` onto stack with replacement
Future<dynamic>? pushReplacementNamed(String destinationRoute, {dynamic arg});
///Pushes `destinationRoute` after popping current route off stack
Future<dynamic>? popAndPushNamed(String destinationRoute, {dynamic arg});
///Pops current route off stack
void goBack();
///Pops routes on stack until `destinationRoute` is hit
void popUntil(String destinationRoute);
///Exits app
void exitApp();
late GlobalKey<NavigatorState> navigatorKey;
}
/// Handles navigation
class NavigationHandlerImpl implements NavigationHandler {
#override
late GlobalKey<NavigatorState> navigatorKey;
/// Constructs a NavigationHandler instance
NavigationHandlerImpl({GlobalKey<NavigatorState>? navigatorKey}) {
this.navigatorKey = navigatorKey ?? GlobalKey<NavigatorState>();
}
NavigatorState? get state => navigatorKey.currentState;
#override
void exitApp() {
SystemChannels.platform.invokeMethod('SystemNavigator.pop');
}
#override
void goBack() {
if (state != null) {
return state!.pop();
}
}
#override
Future? popAndPushNamed(String destinationRoute, {arg}) {
if (state != null) {
return state!.popAndPushNamed(destinationRoute, arguments: arg);
}
}
#override
void popUntil(String destinationRoute) {
if (state != null) {
return state!.popUntil(ModalRoute.withName(destinationRoute));
}
}
#override
Future? pushNamed(String destinationRoute, {arg}) {
if (state != null) {
return state!.pushNamed(destinationRoute, arguments: arg);
}
}
#override
Future? pushNamedAndRemoveUntil(String destinationRoute, String lastRoute,
{arg}) {
if (state != null) {
return state!.pushNamedAndRemoveUntil(
destinationRoute,
ModalRoute.withName(lastRoute),
arguments: arg,
);
}
}
#override
Future? pushReplacementNamed(String destinationRoute, {arg}) {
if (state != null) {
return state!.pushReplacementNamed(destinationRoute, arguments: arg);
}
}
}

flutter-web - Avoid initialRoute from initiating when the app launched with a different route via the browser's address bar?

New to Flutter.
I'm making an app that has a splash screen that initially shows up when the user opens the app. After 3 seconds, the app will show the login or the dashboard screen, depending on the authentication state.
Here's my code.
main.dart
void main() {
runApp(myApp);
}
MaterialApp myApp = MaterialApp(
initialRoute: "/",
routes: {
"/": (context) => SplashScreen(),
"/signin": (context) => SignInScreen(),
"/notes": (context) => NotesScreen(),
},
);
splash_screen.dart
class SplashScreen extends StatefulWidget {
#override
_SplashScreenState createState() => _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
#override
void initState() {
super.initState();
_goToNextScreen();
}
void _goToNextScreen() {
Future.delayed(
Duration(seconds:3),
() async {
AuthState authState = await Auth.getAuthState();
String route = authState == AuthState.SIGNED_IN ? "/notes" : "/signin";
Navigator.pushReplacementNamed(context, route);
}
);
}
// build() override goes here...
}
I've been debugging the app with a web-server. When the app launches with the url localhost:8000/, everything seems fine. However, if the app started with the url localhost:8000/notes, the splash screen, I think, still gets initiated. What happens is the app will show the notes screen, then after 3 seconds, the app will open another notes screen.
Any ideas?
Because first render always started at root '/', it's preferable to use your own path for splash screen, like
initialRoute: '/splash'.
To hide this path in the address bar, replace routes map with route generator:
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
onGenerateRoute: (RouteSettings settings) {
// print current route for clarity.
print('>>> ${settings.name} <<<');
switch (settings.name) {
case '/splash':
return MaterialPageRoute(
builder: (context) => SplashScreen(),
// settings omitted to hide route name
);
case '/signin':
return MaterialPageRoute(
builder: (context) => SignInScreen(),
settings: settings,
);
case '/notes':
return MaterialPageRoute(
builder: (context) => NotesScreen(),
settings: settings,
);
case '/':
// don't generate route on start-up
return null;
default:
return MaterialPageRoute(
builder: (context) => FallbackScreen(),
);
}
},
initialRoute: '/splash',
);
}
}
See since the main logic is we cannot have await in the init state so the page will build irrespective of the any logic you provide. I have a solution to this, there may be some advance or other good solutions too, so this is what I would use.
I would use a concept of future builder. What it will do is wait for my server and then build the whole app.
So process is
In your main.dart
use
Future<void> main() async {
try {
WidgetsFlutterBinding.ensureInitialized();
//await for my server code and according to the variable I get I will take action
//I would have a global parameter lets say int InternetOff
await checkServer();
runApp(MyApp());
} catch (error) {
print(error);
print('Locator setup has failed');
//I can handle the error here
}
}
Now MyApp stateless Widget that will help us choose our path
class MyApp extends Stateless Widget{
Widget build(BuildContext context) {
//Using this FutureBuilder
return FutureBuilder<String>(
builder: (BuildContext context, AsyncSnapshot<String> snapshot) {
// AsyncSnapshot<Your object type>
// Now if InternetOff is equal to one I would make it go to home
if(InternetOff==1) return MaterialApp(
theme: ThemeData.light(),
home: CheckInternet(),
debugShowCheckedModeBanner: false,
);
//else go to Home similarly with these if and else you can add more conditions
else {
return MaterialApp(
theme: ThemeData.dark(),
home: UserHome(),
debugShowCheckedModeBanner: false,
);
}
}
}
},
);
}
}
First of all, flutter-web like any other Single Page Application supports hash based routing. As a result if you want to access
localhost:8000/notes
you have to access it as
localhost:8000/#/notes
Cleaner way to handle auth state
Call getAuthState function before runApp() to make sure that the auth state is set before app is initialized. And pass authState to SplashScreen widget as parameter.
void main() {
WidgetsFlutterBinding.ensureInitialized();
AuthState authState = await Auth.getAuthState();
runApp(MaterialApp myApp = MaterialApp(
initialRoute: "/",
routes: {
"/": (context) => SplashScreen(authState: authState),
"/signin": (context) => SignInScreen(),
"/notes": (context) => NotesScreen(),
},
));
}
splash_screen.dart
class SplashScreen extends StatefulWidget {
final AuthState authState;
SplashScreen({Key key, this.authState}) : super(key: key);
#override
_SplashScreenState createState() => _SplashScreenState();
}
class _SplashScreenState extends State<SplashScreen> {
#override
void initState() {
super.initState();
_goToNextScreen();
}
void _goToNextScreen() {
Future.delayed(
Duration(seconds:3),
() async {
String route = widget.authState == AuthState.SIGNED_IN ? "/notes" : "/signin";
Navigator.pushReplacementNamed(context, route);
}
);
}
#override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: CircularProgressIndicator(),
),
);
}
}
And if you want even more cleaner way to handle auth state, you have to use state management solution like Provider.

Cannot make bottom navigation bar and routing work together in flutter

I am new to flutter and i cannot navigate to new page from bottom navigation bar
I have main app
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
SystemChrome.setSystemUIOverlayStyle(SystemUiOverlayStyle(
statusBarColor: Colors.transparent,
));
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(primarySwatch: Colors.blue),
builder: (BuildContext buildContext, Widget widtget) => Scaffold(
body: RootNavigator(),
bottomNavigationBar: BottomNavigation(),
),
);
}
}
and Rootnavigator
class RootNavigator extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Navigator(
initialRoute: '/',
onGenerateRoute: (RouteSettings settings) {
// final args = settings.arguments;
return MaterialPageRoute(
settings: settings,
builder: (BuildContext context) {
switch (settings.name) {
case '/':
return Page1();
case '/page2':
return Page2();
case '/page3':
return Page3();
default:
return RouteErrorPage();
}
});
},
);
}
}
And bottom navigator
class BottomNavigation extends StatefulWidget {
#override
BottomNavigationState createState() {
return new BottomNavigationState();
}
}
class BottomNavigationState extends State<BottomNavigation> {
int currIndex = 0;
onTap(int index) {
setState(() => currIndex = index);
switch (index) {
case 0:
Navigator.pushNamed(context, '/');
break;
case 1:
Navigator.pushNamed(context, '/page2');
break;
case 2:
Navigator.pushNamed(context, 'page3');
break;
default:
Navigator.push(
context, MaterialPageRoute(builder: (_) => RouteErrorPage()));
}
}
....
// added app bar items
}
Tabs are switching but routes are not. It stays on home page.
I feel like there is something with context but do not know how to solve it.
Can anybody help?
Thanks
p.s. if i move bottom navigation bar to each page separatly everything work sexcept selected tab (because of state) and also i want to keep one, shared app bar
Answer is - #LoVe comment was correct.
Thats how flutter works.
if you have bottom navigation you have to swipe through pages.
Redirection means moving to completely new page and there you have to define Scaffold from sratch.
If you want to have shared AppBar - make it reusable widget

How to use ChangeNotifier with Navigator

In my app, I have a model that store the user logged in my app.
class AuthenticationModel extends ChangeNotifier {
User _user;
User get user => _user;
void authenticate(LoginData loginData) async {
// _user = // get user from http call
notifyListeners();
}
void restoreUser() async {
//_user = // get user from shared prefs
notifyListeners();
}
}
The model is registered at the top of the widget tree :
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return ChangeNotifierProvider(
create: (_) => AuthenticationModel(),
child: MaterialApp(
title: 'My App',
initialRoute: '/',
routes: {
'/': (context) => PrehomeScreen(),
'/home': (context) => HomeScreen()
},
),
);
}
}
Somewhere down the widget tree, I have a button that calls the Model :
child: Consumer<AuthenticationModel>(
builder: (context, authModel, child) {
return MyCustomButton(
text: 'Connect',
onPressed: () {
authModel.authenticate(...)
},
);
},
),
Now, I would like, somewhere, listen to the changes on the AuthenticationModel to trigger a Navigator.pushReplacmentNamed('/home') when the user is not null in the model.
I tried to do it in the builder of Prehome :
class PrehomeScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return Consumer<AuthenticationModel>(
builder: (context, authModel, child) {
if (authModel.user != null) {
Navigator.of(context).pushReplacementNamed("/home")
}
return Container(
child: // Prehome UI
);
},
);
}
}
but I have a error when doing it like this :
════════ (2) Exception caught by widgets library ═══════════════════════════════════════════════════
setState() or markNeedsBuild() called during build.
The relevant error-causing widget was:
Consumer<AuthenticationModel> file:///Users/pierre.degand/Projects/cdc/course_du_coeur/lib/Prehome.dart:13:12
═══════════════════════════════════════════════════════════════════════════════
How can I setup such a listener ? Is it a good practice to trigger navigation on model changes like this ?
Thanks
EDIT: I found a way to make this work. Instead of using Consumer inside the PrehomeScreen builder, I used the following code :
class PrehomeScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
Provider.of<AuthenticationModel>(context).addListener(() {
Navigator.of(context).pushReplacementNamed("/home");
});
return Container(
child: // UI
);
}
}
It works fine, the navigation is executed when the model changes. But there is an error message in the console (printed 3 times) :
════════ (4) Exception caught by foundation library ════════════════════════════════════════════════
Looking up a deactivated widget's ancestor is unsafe.
════════════════════════════════════════════════════════════════════════════════════════════════════
The app does not crash so, for now, I'm ok with this.
I still want to know if this is a good approach or not.
I prefer to use Stream or rxdart PublishSubject BehaviourSubject for listening to any activity or to manage global app data.
I implement it using bloc pattern. Basically bloc pattern is just like redux for react means creating a central dataset that contains all app data and you don't have to do prop drilling.
You can create Stream like this.
import 'package:rxdart/rxdart.dart';
class AbcBloc {
BehaviorSubject<bool> _connectivity;
AbcBloc() {
_connectivity = BehaviorSubject<bool>();
}
// stream
Stream<bool> get connectivity => _connectivity.stream;
// sink
Function(bool) get updateConnectivity => _connectivity.sink.add;
dispose(){
_connectivity.close();
}
}
void createAbcBloc() {
if (abcBloc != null) {
abcBloc.dispose();
}
abcBloc = AbcBloc();
}
AbcBloc abcBloc = AbcBloc();
now you can access that abcBloc variable from anywhere and listen to connectivity variable like this
import './abcBloc.dart';
void listenConnectivity(){
abcBloc.connectivity.listen((bool connectivety){
here you can perform your operations
});
}
and you can update connectivity from abcBloc.updateConnectivity(false);
every time you perform any changes that listener will get called.
remember you have to call listenConnectivity() one time to get it activated;
void main() {
Provider.debugCheckInvalidValueType = null;
return runApp(
Provider(
create: (_) => AuthenticationModel(),
child: MyApp(),
),
);
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
final navigatorKey = GlobalKey<NavigatorState>();
Provider.of<AuthenticationModel>(context).addListener(() {
final authModel = Provider.of<AuthenticationModel>(context);
if (authModel.user != null) {
navigatorKey.currentState.pushReplacementNamed("/home");
}
});
return MaterialApp(
navigatorKey: navigatorKey,
title: 'My App',
initialRoute: '/',
routes: {
'/': (context) => PrehomeScreen(),
'/home': (context) => HomeScreen()
},
);
}
}
I don't think ChangeNotifier is needed.
void main() async {
final isLoggedIn = await Future.value(true); // get value from shared prefs or your model
runApp(MyApp(isLoggedIn));
}
class MyApp extends StatelessWidget {
MyApp(this.isLoggedIn);
final bool isLoggedIn;
#override
Widget build(BuildContext context) {
return MaterialApp(
initialRoute: isLoggedIn ? '/home' : '/',
routes: {
'/': (context) => HomeScreen(),
'/login': (context) => LoginScreen()
},
);
}
}
class HomeScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return RaisedButton(
child: Text('Logout'),
onPressed: () => Navigator.of(context).pushReplacementNamed("/login"),
);
}
}
class LoginScreen extends StatelessWidget {
#override
Widget build(BuildContext context) {
return RaisedButton(
child: Text('Login'),
onPressed: () => Navigator.of(context).pushReplacementNamed("/"),
);
}
}

Flutter pass argument directly with named routes navigation

I have been looking at all the answers on here to pass arguments when doing named route navigation but they seem to be old answers or they don't work.
From what was written it should be working but it doesn't seem to do anything, so I am not sure where my error is.
This is how I have it setup:
Main.dart (With my named routes setup):
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primaryColor: Colors.white,
),
initialRoute: HomePageScreen.id,
routes: {
HomePageScreen.id: (context) => HomePageScreen(),
AddItemScreen.id: (context) => AddItemScreen(),
AdvertiseScreen.id: (context) => AdvertiseScreen(),
HomePageFilterScreen.id: (context) => HomePageFilterScreen(),
HomePageResultsScreen.id: (context) => HomePageResultsScreen(),
ItemPageProfileScreen.id: (context) => ItemPageProfileScreen(),
ItemPageProfileSuggestUpdateScreen.id: (context) => ItemPageProfileSuggestUpdateScreen(),
ItemPageWhereToBuyAddStoreToDatabaseScreen.id: (context) => ItemPageWhereToBuyAddStoreToDatabaseScreen(),
ItemPageWhereToBuyMapScreen.id: (context) => ItemPageWhereToBuyMapScreen(),
ItemPageWhereToBuyScreen.id: (context) => ItemPageWhereToBuyScreen(),
MenuScreen.id: (context) => MenuScreen(),
NotAvailableScreen.id: (context) => NotAvailableScreen(),
TermsScreen.id: (context) => TermsScreen(),
}
);
}
}
HomePageResultsScreen.dart (On button click I am using push named to navigate to the next page, this is working because the new page 'ItemPageProfileScreen is opening):
onTap: () {
Navigator.pushNamed(context, ItemPageProfileScreen.id, arguments: 'MyTestString');
}
ItemPageProfileScreen.dart (I have tried using MaterialApp onGenerateRoute to get the arguments and print to screen to test but it is not working):
class ItemPageProfileScreen extends StatefulWidget {
static const String id = 'item_page_profile_screen';
#override
_ItemPageProfileScreenState createState() => _ItemPageProfileScreenState();
}
class _ItemPageProfileScreenState extends State<ItemPageProfileScreen> {
#override
Widget build(BuildContext context) {
MaterialApp(
onGenerateRoute: (routeSettings){
final arguments = routeSettings.arguments;
print(arguments.toString());
},
);
return Scaffold(),
Thanks for your help.
EDIT Second attempt:
class ItemPageProfileScreen extends StatefulWidget {
final String argument;
ItemPageProfileScreen(this.argument);
static const String id = 'item_page_profile_screen';
#override
_ItemPageProfileScreenState createState() => _ItemPageProfileScreenState();
}
class _ItemPageProfileScreenState extends State<ItemPageProfileScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
body: SingleChildScrollView(
child: Column(
children: <Widget>[
Text(widget.argument),
There is an official article on how to pass arguments with named routing. https://flutter.dev/docs/cookbook/navigation/navigate-with-arguments
The main idea is pretty straightforward: pass arguments into the constructor of your screen widget.
In the official docs (in the link above) they actually used both approaches with named routing and with regular routing even though the article stated about named routing.
Anyways. Focus on the constructor and arguments.
Where can you access the constructor of your screen with named routing if you pass only the name of the route when you navigate? In onGenerateRoute method. Let's do it.
Overwrite onGenerateRoute method in your top screen MyApp (that's where your mistake was). And if you do it you don't need routes: {} there (your second mistake)
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primaryColor: Colors.white,
),
initialRoute: HomePageScreen.id,
onGenerateRoute: (settings) {
if(settings.name == ItemPageProfileScreen.id) {
String msg = settings.arguments;
return MaterialPageRoute(builder: (_) => ItemPageProfileScreen(msg));
} else if(...
},
Get the arguments from the widget constructor:
class ItemPageProfileScreen extends StatefulWidget {
final String argument;
ItemPageProfileScreen(this.argument);
static const String id = 'item_page_profile_screen';
#override
_ItemPageProfileScreenState createState() => _ItemPageProfileScreenState();
}
class _ItemPageProfileScreenState extends State<ItemPageProfileScreen> {
#override
Widget build(BuildContext context) {
String msg = widget.argument;
...
And sending arguments over on tap:
onTap: () {Navigator.pushNamed(context, ItemPageProfileScreen.id, arguments: 'MyTestString');}
Hope this helps.