Flutter setState () или markNeedsBuild () вызывается при блокировке дерева виджетов
у меня возникли проблемы с поиском источника этого исключения, и приложение довольно сложное, поэтому трудно показать какую-либо соответствующую часть кода. Это мой репозиторий в точке, где происходит ошибка: GitHub РЕПО
Я подозреваю, что преступником может быть следующий код:
Widget buildResultCard(Map result, BuildContext context) {
String name = result["value"];
String description =
result["label"].replaceAll(new RegExp(r"<(?:.|n)*?>"), "");
TextEditingController controller = new TextEditingController(text: name);
Function onPressed = () {
showDialog(
context: context,
child: new AlertDialog(
title: new Text("Name your schedule"),
content: new TextField(
autofocus: true,
controller: controller,
),
actions: <Widget>[
new FlatButton(
onPressed: () {
String givenName = controller.text;
ScheduleMeta schedule = new ScheduleMeta(
givenName: givenName,
name: name,
type: _selectedChoice.value,
description: description);
scheduleStore
.dispatch(new AddScheduleAction(schedule: schedule));
scheduleStore.dispatch(
new SetCurrentScheduleAction(schedule: schedule));
fetchAllSchedules(scheduleStore.state.schedules)
.then((weeks) {
scheduleStore.dispatch(
new SetWeeksForCurrentScheduleAction(weeks: weeks));
});
Scaffold.of(context).showSnackBar(new SnackBar(
content: new Text("Added " + givenName),
action: new SnackBarAction(
label: "Undo",
onPressed: () {
scheduleStore.dispatch(
new RemoveScheduleAction(schedule: name));
Scaffold.of(context).showSnackBar(new SnackBar(
content: new Text(
"Deleted " + givenName),
));
}),
));
Navigator.of(context).pop();
},
child: new Text("Add")),
],
));
};
return new Card(
child: new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new ListTile(
leading: const Icon(Icons.schedule),
title: new Text(name),
subtitle: new Text(description),
isThreeLine: true,
dense: true,
),
new ButtonTheme.bar(
child: new ButtonBar(
children: <Widget>[
new FlatButton(
child: const Text('Add Schedule'),
onPressed: scheduleStore.state.schedules
.any((schedule) => schedule.name == name)
? null
: onPressed)
],
),
),
],
),
);
}
ошибка появляется при отображении диалогового окна, и когда пользователь нажимает кнопку в диалоговом окне, два Redux store отправляются непосредственно друг за другом. Этот Пользовательский интерфейс за диалогом подписывается на изменения в хранилище Redux.
Я думал, что Dart / Flutter был однопоточным, поэтому такого столкновения не могло произойти, где кажется, что поток вызывает setState() на виджете, а другой поставил блокировку на дереве виджета.
есть ли способ проверить, заблокировано ли дерево виджетов, чтобы этого можно было избежать?
стек предоставляет эту информацию:
I/flutter (13466): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter (13466): The following assertion was thrown while finalizing the widget tree:
I/flutter (13466): setState() or markNeedsBuild() called when widget tree was locked.
I/flutter (13466): This _ModalScope widget cannot be marked as needing to build because the framework is locked.
I/flutter (13466): The widget on which setState() or markNeedsBuild() was called was:
I/flutter (13466): _ModalScope([LabeledGlobalKey<_ModalScopeState>#cb4cc]; state: _ModalScopeState#d4c02())
I/flutter (13466):
I/flutter (13466): When the exception was thrown, this was the stack:
I/flutter (13466): #0 Element.markNeedsBuild.<anonymous closure> (package:flutter/src/widgets/framework.dart:3250)
I/flutter (13466): #2 Element.markNeedsBuild (package:flutter/src/widgets/framework.dart:3226)
I/flutter (13466): #3 State.setState (package:flutter/src/widgets/framework.dart:1072)
I/flutter (13466): #4 _ModalScopeState._routeSetState (package:flutter/src/widgets/routes.dart:473)
I/flutter (13466): #5 ModalRoute.setState (package:flutter/src/widgets/routes.dart:552)
I/flutter (13466): #6 ModalRoute.changedInternalState (package:flutter/src/widgets/routes.dart:889)
I/flutter (13466): #7 TransitionRoute&&LocalHistoryRoute.removeLocalHistoryEntry (package:flutter/src/widgets/routes.dart:317)
I/flutter (13466): #8 LocalHistoryEntry.remove (package:flutter/src/widgets/routes.dart:267)
I/flutter (13466): #9 DrawerControllerState.dispose (package:flutter/src/material/drawer.dart:147)
I/flutter (13466): #10 StatefulElement.unmount (package:flutter/src/widgets/framework.dart:3550)
I/flutter (13466): #11 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1626)
I/flutter (13466): #12 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #13 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #14 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #15 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #16 MultiChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:4421)
I/flutter (13466): #17 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #18 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #19 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #20 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #21 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #22 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #23 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #24 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #25 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:4321)
I/flutter (13466): #26 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #27 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #28 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #29 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #30 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #31 SingleChildRenderObjectElement.visitChildren (package:flutter/src/widgets/framework.dart:4321)
I/flutter (13466): #32 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #33 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #34 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #35 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #36 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #37 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #38 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #39 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #40 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #41 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #42 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #43 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #44 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #45 _InactiveElements._unmount.<anonymous closure> (package:flutter/src/widgets/framework.dart:1624)
I/flutter (13466): #46 ComponentElement.visitChildren (package:flutter/src/widgets/framework.dart:3427)
I/flutter (13466): #47 _InactiveElements._unmount (package:flutter/src/widgets/framework.dart:1622)
I/flutter (13466): #48 _InactiveElements._unmountAll (package:flutter/src/widgets/framework.dart:1636)
I/flutter (13466): #49 BuildOwner.finalizeTree.<anonymous closure> (package:flutter/src/widgets/framework.dart:2228)
I/flutter (13466): #50 BuildOwner.lockState (package:flutter/src/widgets/framework.dart:2060)
I/flutter (13466): #51 BuildOwner.finalizeTree (package:flutter/src/widgets/framework.dart:2227)
I/flutter (13466): #52 BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding&WidgetsBinding.drawFrame (package:flutter/src/widgets/binding.dart:505)
I/flutter (13466): #53 BindingBase&SchedulerBinding&GestureBinding&ServicesBinding&RendererBinding._handlePersistentFrameCallback (package:flutter/src/rendering/binding.dart:189)
I/flutter (13466): #54 BindingBase&SchedulerBinding._invokeFrameCallback (package:flutter/src/scheduler/binding.dart:688)
I/flutter (13466): #55 BindingBase&SchedulerBinding.handleDrawFrame (package:flutter/src/scheduler/binding.dart:636)
I/flutter (13466): #56 _drawFrame (file:///b/build/slave/Linux_Engine/build/src/flutter/lib/ui/hooks.dart:70)
I/flutter (13466): (elided one frame from class _AssertionError)
I/flutter (13466): ════════════════════════════════════════════════════════════════════════════════════════════════════
1 ответов
это не проблема потока. Эта ошибка означает, что вы вызываете setState на этапе сборки.
типичным примером может быть следующее :
Widget build(BuildContext context) {
setState(() { print("foo"); });
return Container();
}
но вызов setState может быть менее очевидным. Например,Navigator.pop(context) тут setState внутренне. Итак, следующее:
Widget build(BuildContext context) {
Navigator.pop(context);
return Container();
}
также не идет.
глядя на stacktrace кажется, что одновременно с Navigator.pop(context) ваш модальный попробуйте обновить с новыми данными.