flutter return data from a screen error with pushNamed()

Question

I use pushNamed() to get return data from screen like this:

_pushToPage2() async {
    String result = await Navigator.pushNamed(context, "/page2");
    print("$tag $result");
}

But there was something wrong with the code, this the full error stack trace:

E/flutter: [ERROR:flutter/shell/common/shell.cc(181)] Dart Error: Unhandled exception:
type 'MaterialPageRoute' is not a subtype of type 'Route'
0 NavigatorState._routeNamed (package:flutter/src/widgets/navigator.dart:1408:14)
1 NavigatorState.pushNamed (package:flutter/src/widgets/navigator.dart:1454:20)
2 _MyHomePageState._pushToPage2 (file:///Users/wang/flutter_project/flutter_navigation/lib/main.dart:113:50)
3 _MyHomePageState.build. (file:///Users/wang/flutter_project/flutter_navigation/lib/main.dart:58:19)
4 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
5 _InkResponseState.build. (package:flutter/src/material/ink_well.dart:562:30)
6 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
7 TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
8 TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
9 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
10 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
11 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
12 _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:143:19)
13 _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
14 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
15 _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
16 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
17 _invoke1 (dart:ui/hooks.dart:153:13)
18 _dispatchPointerDataPacket (dart:ui/hooks.dart:107:5)

But the following code is working properly:

_pushToPage2() async {
    String result = await Navigator.push(
         context, MaterialPageRoute(builder: (context) => Page2()));
    print("$tag $result");
}

Answer 1

I have a same problem. And finally I found a solution. Cast your result to your type.

For example:

String result = await Navigator.of(context).pushNamed("/some_route")

The code above will raise the exception.

But, you can do like this:

final result = await Navigator.of(context).pushNamed("/some_route") as String;

The code above will work as expected.

Answer 2

Just declare the working type Page2 for MaterialPageRoute in the router

case "/page2":
  return MaterialPageRoute<Page2>(...};