Navigator.removeRoute & Navigator.removeRouteBelow - flutter

Question

There are two functions in Navigator.dart, removeRoute and removeRouteBelow. I don't know how to use these two methods. This is the page route: / -> A -> B -> C -> D. And I perform this code in page D:
Navigator.removeRoute(context, MaterialPageRoute(builder: (context) => PushPageB()));
But there goes something wrong：
══╡ EXCEPTION CAUGHT BY GESTURE ╞═════════════════════════════════
The following assertion was thrown while handling a gesture:
'package:flutter/src/widgets/navigator.dart': Failed assertion: line 1832 pos 12: 'route._navigator
== this': is not true.
Either the assertion indicates an error in the framework itself, or we should provide substantially
more information in this error message to help you determine and fix the underlying cause.
In either case, please report this assertion by filing a bug on GitHub:
https://github.com/flutter/flutter/issues/new
When the exception was thrown, this was the stack:
2 NavigatorState.removeRoute (package:flutter/src/widgets/navigator.dart:1832:12)
3 Navigator.removeRoute (package:flutter/src/widgets/navigator.dart:1221:34)
4 PushPageE.build.<anonymous closure> (package:flutter_navigation/push_page_1.dart:223:29)
5 _InkResponseState._handleTap (package:flutter/src/material/ink_well.dart:507:14)
6 _InkResponseState.build.<anonymous closure> (package:flutter/src/material/ink_well.dart:562:30)
7 GestureRecognizer.invokeCallback (package:flutter/src/gestures/recognizer.dart:102:24)
8 TapGestureRecognizer._checkUp (package:flutter/src/gestures/tap.dart:242:9)
9 TapGestureRecognizer.handlePrimaryPointer (package:flutter/src/gestures/tap.dart:175:7)
10 PrimaryPointerGestureRecognizer.handleEvent (package:flutter/src/gestures/recognizer.dart:315:9)
11 PointerRouter._dispatch (package:flutter/src/gestures/pointer_router.dart:73:12)
12 PointerRouter.route (package:flutter/src/gestures/pointer_router.dart:101:11)
13 _WidgetsFlutterBinding&BindingBase&GestureBinding.handleEvent (package:flutter/src/gestures/binding.dart:143:19)
14 _WidgetsFlutterBinding&BindingBase&GestureBinding.dispatchEvent (package:flutter/src/gestures/binding.dart:121:22)
15 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerEvent (package:flutter/src/gestures/binding.dart:101:7)
16 _WidgetsFlutterBinding&BindingBase&GestureBinding._flushPointerEventQueue (package:flutter/src/gestures/binding.dart:64:7)
17 _WidgetsFlutterBinding&BindingBase&GestureBinding._handlePointerDataPacket (package:flutter/src/gestures/binding.dart:48:7)
18 _invoke1 (dart:ui/hooks.dart:153:13)
19 _dispatchPointerDataPacket (dart:ui/hooks.dart:107:5)
(elided 2 frames from class _AssertionError)
Handler: onTap
Recognizer:
TapGestureRecognizer#2a91c(debugOwner: GestureDetector, state: possible, won arena, finalPosition:
Offset(211.1, 411.1), sent tap down)
══════════════════════════════════════════════════════════════════
I don't know why would this happened, and how use these two methods correctly.

Answer 1

The MaterialPageRoute you have created inside Navigator.removeRoute call has no connection to the Navigator because it wasn't pushed yet. Therefore you've got an error.
In order to use removeRoute method correctly you need to remeber a route you pushed to the Navigator.
I am using following code to keep just one instance of a page in the Navigator.
var filterRoutes = <String, MaterialPageRoute<dynamic>>{'page1': null, 'page2': null, 'page3': null, 'page4': null};
MaterialPageRoute getNextRoute(BuildContext context, String nextPage) {
var route;
switch (nextPage) {
case 'page1':
route = MaterialPageRoute(builder: (context) => Page1());
break;
case 'page2':
route = MaterialPageRoute(builder: (context) => Page2());
break;
case 'page3':
route = MaterialPageRoute(builder: (context) => Page3());
break;
case 'page4':
route = MaterialPageRoute(builder: (context) => Page4());
break;
default:
route = MaterialPageRoute(builder: (context) => SomeOtherPage());
}
if (nextPage != null) {
if (filterRoutes[nextPage] != null) {
Navigator.removeRoute(context, filterRoutes[nextPage]);
}
filterRoutes[nextPage] = route;
}
return route;
}

Answer 2

If you want to remove blow router and go to new route like logout from setting and go to login page, you can do this:
Navigator.of(context).pushAndRemoveUntil(MaterialPageRoute(builder: (context) =>
LoginScreen()), (Route<dynamic> route) => false);