How to create Flutter route for Stateful Widget?

Question

I'm getting the Navigator operation requested with a context that does not include a Navigator. error log for my Flutter app. All the examples I see are for "Stateless" widgets so I think this may be the issue or my code? How can I route to my LoginPage? Here is my code without any Navigator or route...

 void main() {
      runApp(new MyApp());
    }

    final googleSignIn = new GoogleSignIn();
    final fb = FirebaseDatabase.instance.reference();
    final auth = FirebaseAuth.instance;

    class MyApp extends StatefulWidget {
      @override
      _MyAppState createState() => new _MyAppState();
    }

    class _MyAppState extends State<MyApp> {
      String _platformVersion = 'Unknown';

      @override
      initState() {
        super.initState();
        initPlatformState();
      }

      // Platform messages are asynchronous, so we initialize in an async method.
      initPlatformState() async {
        String platformVersion;
        // Platform messages may fail, so we use a try/catch PlatformException.
        try {
          platformVersion = await Myfavkpopflutter.platformVersion;
        } on PlatformException {
          platformVersion = 'Failed to get platform version.';
        }

        // If the widget was removed from the tree while the asynchronous platform
        // message was in flight, we want to discard the reply rather than calling
        // setState to update our non-existent appearance.
        if (!mounted) return;

        setState(() {
          _platformVersion = platformVersion;
        });
      }

      void MyFavAction() {
        setState(() {
          print("MYFAV");

    //      fb.child("messages").orderByValue().onChildAdded.listen((Event event) {
    //        print('Child added: ${event.snapshot.value}');
    //      });
        });
      }

      void SearchAction() {
        setState(() {
          print("Search");
        });
      }



      @override
      Widget build(BuildContext context) {
        if (auth.currentUser == null) {
          return new MaterialApp(
            routes: <String, WidgetBuilder>{
            '/settings': (BuildContext context) => new LoginPage(),
            },
            home: new Scaffold(
              backgroundColor: Colors.white70,
              appBar: new AppBar(
                title: new Text(
                  "MyFavKPop",
                  style: new TextStyle(
                      color: Colors.black,
                      fontWeight: FontWeight.bold,
                      fontSize: 25.00),
                ),
                backgroundColor: Colors.amber,
              ),
              body: new Container(
                  child: new Center(
                      child: new Column(
                mainAxisAlignment: MainAxisAlignment.center,
                children: <Widget>[
                  new RaisedButton(
                    onPressed: MyFavAction,
                    color: Colors.lightBlue,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    child: new Text(
                      "MyFav KPOP",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(padding: new EdgeInsets.all(30.00)),
                  new RaisedButton(
                    onPressed: SearchAction,
                    color: Colors.lightBlue,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    child: new Text(
                      "MyFav SEARCH",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(padding: new EdgeInsets.all(30.00),
                  ),
                  new RaisedButton(
                    onPressed: SearchAction,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    color: Colors.lightBlue,
                    child: new Text(
                      "MyFav FRIENDS",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(
                    padding: new EdgeInsets.all(30.00),
                  ),
                  new RaisedButton(
                    onPressed: SearchAction,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    color: Colors.lightBlue,
                    child: new Text(
                      "MyFav CHAT",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  ),
                  new Padding(
                    padding: new EdgeInsets.all(30.00),
                  ),
                  new RaisedButton(
                    onPressed: SearchAction,
                    elevation: 20.00,
                    splashColor: Colors.amber,
                    color: Colors.lightBlue,
                    child: new Text(
                      "MyFav #1'S",
                      style: new TextStyle(color: Colors.black, fontSize: 20.00),
                    ),
                  )
                ],
              ))),
              floatingActionButton: new FloatingActionButton(
                  child: new Text(
                    "Log Out",
                    style: new TextStyle(fontWeight: FontWeight.bold, fontSize: 12.00),
                  ),
                  onPressed: () => Navigator.of(context).pushNamed('/settings'),,
            ),
          ));
        } 
      }
    }

    class LoginPage extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: new AppBar(
        title: new Text("Login / Signup"),
      ),
      body: new Container(
        child: new Center(
          child: new Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              new TextField(
                decoration: new InputDecoration(
                    hintText: "E M A I L    A D D R E S S"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new TextField(
                obscureText: true,
                decoration:
                new InputDecoration(hintText: "P A S S W O R D"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new TextField(
                decoration:
                new InputDecoration(hintText: "U S E R N A M E"),
              ),
              new RaisedButton(
                onPressed: null,
                child: new Text("SIGNUP"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new RaisedButton(
                onPressed: null,
                child: new Text("LOGIN"),
              ),
              new Padding(padding: new EdgeInsets.all(15.00)),
              new RaisedButton(
                onPressed: null,
                child: new Text("Facebook"),
              ),
              new Padding(padding: new EdgeInsets.all(5.00)),
              new RaisedButton(
                onPressed: null,
                child: new Text("Google"),
              )
            ],
          ),
        ),
        margin: new EdgeInsets.all(15.00),
      ),
    );
  }
}

**** EDIT Here is the error log I'm getting...

══╡ EXCEPTION CAUGHT BY GESTURE ╞═══════════════════════════════════════════════════════════════════ The following assertion was thrown while handling a gesture: Navigator operation requested with a context that does not include a Navigator. The context used to push or pop routes from the Navigator must be that of a widget that is a descendant of a Navigator widget.

════════════════════════════════════════════════════════════════════════════════════════════════════

Answer 1

You stated in the title that your problem is navigating to a StatefulWidget while in your post you are asking about how to navigate to a StatelessWidget LoginPage.

Anyhow, you should be able to implement navigating the same way regardless of the state matter.

Try to follow the following flow which is taken from an app I am working on.

//Local Imports
//MyTabs.dart is where I define my home page which is a StatefulWidget with TabBarView 
import 'MyTabs.dart' as first;

.....

//My main function where I start my app

    void main() {
      runApp( new MaterialApp(
        home: new SignIn(),
        routes: <String, WidgetBuilder>{
          "/mytabs" : (BuildContext context)=> new first.MyTabs(),
          //add more routes here
        },

      ));
    }

My app starts with a SignIn page, I have created a simpler one than I have to show the idea

class SignIn extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
  return new Scaffold(
    appBar: new AppBar(
      title: new Text("Sign In"),
    ),
    body: new IconButton(icon: new Icon(Icons.arrow_forward), onPressed: (){Navigator.of(context).pushNamed("/mytabs");}),
  )

I hope I was of any help, try to follow this flow in your code and let me know how it went.

Answer 2

Navigator.of(context).push(new MaterialPageRoute(builder: 
                   (BuildContext context) => new MyTabs()));

For navigation, we can use the above code also.