Sch*_*sch 16 dart redux flutter
我无法找到此异常的来源,并且应用程序非常复杂,因此很难显示代码的任何相关部分.这是我在错误发生时的存储库: Github repo
我怀疑以下代码可能是犯罪者:
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)
],
),
),
],
),
);
}
显示对话框时出现错误,当用户按下对话框上的按钮时,两个Redux存储调度将直接相继发送.对话框后面的UI订阅了Redux商店中的更改.
我认为Dart/Flutter是单线程的,因此不会发生这样的冲突,看起来线程在一个小部件上调用setState()而另一个在小部件树上放置了锁.
有没有办法检查小部件树是否被锁定,这样可以避免？
堆栈提供此信息:
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): ????????????????????????????????????????????????????????????????????????????????????????????????????
Den*_*din 33
使用Scaffoldand 的Drawer特殊情况：
如果您尝试使用 opens 重建树，也会发生这种失败Drawer。例如，如果您向Bloc强制重建整个页面/屏幕的消息发送消息。
考虑Navigator.pop(context)首先在您的点击处理程序中调用。
And*_*eev 30
作为一种变通方法包装你的代码，调用setState到WidgetsBinding.addPostFrameCallback:
WidgetsBinding.instance
.addPostFrameCallback((_) => setState(() {}));
这样您就可以确保在构建当前小部件后执行它。
Rém*_*let 18
这不是一个线程问题.此错误表示您setState在构建阶段进行调用.
一个典型的例子如下:
Widget build(BuildContext context) {
myParentWidgetState.setState(() { print("foo"); });
return Container();
}
但是setState调用可能不太明显.例如,a Navigator.pop(context)在setState内部执行.所以以下内容:
Widget build(BuildContext context) {
Navigator.pop(context);
return Container();
}
也不是.
看看堆栈跟踪,似乎与Navigator.pop(context) 您的模态同时尝试使用新数据进行更新.
Blo*_*oss 11
方法setState内部和外部使用了几个选项buildcontextinitState
将您的 setState 包装在其中之一中
WidgetsBinding.instance.addPostFrameCallback或Future.microTask()或Timer.run或Future.delayed(Duration.zero,
例子：
WidgetsBinding.instance
.addPostFrameCallback((_) {
//valueNotifier.value = _pcm; //provider
//setState
});
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