多个小部件使用相同的GlobalKey [英] Multiple widgets used the same GlobalKey
本文介绍了多个小部件使用相同的GlobalKey的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我正在使用Flutter。我有一个带有3个标签的简单应用。每个带有ListView的选项卡中都有一个RefreshIndicator。这些行是用另一种方法构建的。
这是代码：
@override
小部件构建（BuildContext上下文）{
最后的GlobalKey< RefreshIndicatorState> _RIKey1 = new GlobalKey< RefreshIndicatorState>（）;
final GlobalKey< RefreshIndicatorState> _RIKey2 = new GlobalKey< RefreshIndicatorState>（）;
final GlobalKey< RefreshIndicatorState> _RIKey3 = new GlobalKey< RefreshIndicatorState>（）;
debugPrint（_RIKey1.toString（））;
debugPrint（_RIKey2.toString（））;
debugPrint（_RIKey3.toString（））;
返回新的Scaffold（
主体：new DefaultTabController（
长度：3，
子代：new Scaffold（
appBar：new AppBar（
bottom：new TabBar（
标签：[
新标签（icon：新Icon（Icons.view_list））），
新标签（icon：new Icon（Icons.hotel）），
新Tab（icon：new Icon（Icons.assesssmentment）），
]，
），
title：new Text（'Data'），
），
body ：新的TabBarView（
子项：[
新的RefreshIndicator（
项：_RIKey1，
onRefresh：_actualizoData，
子项：new ListView.builder（
padding ：new EdgeInsets.only（top：5.0），
itemCount：linea_reservas.length * 2，
itemBuilder：（BuildContext上下文，int位置）{
if（positi on.isOdd）返回新的Divider（）;
最终索引=位置〜/ 2;
return _buildRow（index）;
}），
），
新的RefreshIndicator（
键：_RIKey2，
onRefresh：_actualizoData，
子级：new ListView.builder（
填充：new EdgeInsets.only（顶部：8.0），
itemCount：linea_inouthouse.length * 2，
itemBuilder：（BuildContext上下文，int position）{
if（position.isOdd）return new Divider（）;
最终索引=位置〜/ 2;
return _buildRowInOutHouse（index）;
}），
），
新RefreshIndicator（
键：_RIKey3，
刷新：_actualizoData，
子级：new ListView.builder（
padding：new EdgeInsets.only（top：5.0），
itemCount：linea_ocupacion.length * 2，
它emBuilder：（BuildContext context，int position）{
if（position.isOdd）返回新的Divider（）;
最终索引=位置〜/ 2;
return _buildRowOcupacion（index）;
}），
），
]，
），
），
），
）；
}
我添加了debugPrints，输出为6行，而不是3行
I / flutter（5252）：[LabeledGlobalKey< RefreshIndicatorState>＃4d76c]
I / flutter（5252） ：[LabeledGlobalKey< RefreshIndicatorState>＃59b9e]
I / flutter（5252）：[LabeledGlobalKey< RefreshIndicatorState>＃2c88b]
I / flutter（5252）：[LabeledGlobalKey< RefreshIndicatorStateb&d] 42 b I / Flutter（5252）：[LabeledGlobalKey< RefreshIndicatorState>＃1c984]
I / flutter（5252）：[LabeledGlobalKey< RefreshIndicatorState&＃; $ p>
该应用程序正常运行，但是几次更改标签后，它因以下错误而崩溃：
I / flutter（5252）：W小工具库引起的异常CA ══════════════════════════════════════
I / flutter（5252）：引发断言之后，构建NotificationListener< KeepAliveNotification&g t;：
I / flutter（5252）：多个小部件使用了相同的GlobalKey。
I / flutter（5252）：键[LabeledGlobalKey< RefreshIndicatorState>＃7bd42]被多个小部件使用。
I / flutter（5252）的父母：这些小部件是：
I / flutter（5252）：-RepaintBoundary-[< [LabeledGlobalKey< RefreshIndicatorState>＃7bd42]>]（renderObject：
I / flutter（5252）：RenderRepaintBoundary＃60a4a分离）
I / flutter（5252）：-RepaintBoundary-[< [LabeledGlobalKey< RefreshIndicatorState>＃7bd42]>]（renderObject：
I / flutter（5252）：RenderRepaintBoundary＃c8cdb NEEDS-LAYOUT NEEDS-PAINT）
I / flutter（5252）：只能在小部件树中一次在一个小部件上指定GlobalKey。
键是在Build方法中生成的，所以，我不明白为什么多个小部件使用了相同的GlobalKey 错误
为什么再次生成密钥，为什么它不是唯一的？我并不是在说一千个意图，在选项卡之间切换4或5次后，错误就会出现。
谢谢您的帮助。
解决方案您可以手动创建密钥并使用静态/常量值吗？例如...
import‘package：flutter / widgets.dart’;
类RIKeys {
static final riKey1 = const Key（’__ RIKEY1__’）;
static final riKey2 = const Key（’__ RIKEY2__’）;
static final riKey3 = const Key（’__ RIKEY3__’）;
}
然后在...
正文：new TabBarView（
子级：[
new RefreshIndicator（new RefreshIndicator（
// //使用手动静态值代替...
键：RIKeys.riKey1，
刷新：_actualizoData，
子级：new ListView.builder（
padding：new EdgeInsets.only（top：5.0），
itemCount ：linea_reservas.length * 2，
itemBuilder：（BuildContext上下文，int position）{
if（position.isOdd）return new Divider（）;
final index = position〜/ 2;
return _buildRow（index）;
}），
），
我在类似情况下也取得了一些成功……尤其是在redux或其他类似模式下……
I'm using Flutter. I have a simple app with 3 tabs. There is a RefreshIndicator in each tab with a ListView. The rows are built in another method.
This is the code:
@override
Widget build(BuildContext context) {
final GlobalKey<RefreshIndicatorState> _RIKey1 = new GlobalKey<RefreshIndicatorState>();
final GlobalKey<RefreshIndicatorState> _RIKey2 = new GlobalKey<RefreshIndicatorState>();
final GlobalKey<RefreshIndicatorState> _RIKey3 = new GlobalKey<RefreshIndicatorState>();
debugPrint(_RIKey1.toString());
debugPrint(_RIKey2.toString());
debugPrint(_RIKey3.toString());
return new Scaffold(
body: new DefaultTabController(
length: 3,
child: new Scaffold(
appBar: new AppBar(
bottom: new TabBar(
tabs: [
new Tab(icon: new Icon(Icons.view_list)),
new Tab(icon: new Icon(Icons.hotel)),
new Tab(icon: new Icon(Icons.assessment)),
],
),
title: new Text('Data'),
),
body: new TabBarView(
children: [
new RefreshIndicator(
key: _RIKey1,
onRefresh: _actualizoData,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 5.0),
itemCount: linea_reservas.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRow(index);
}),
),
new RefreshIndicator(
key: _RIKey2,
onRefresh: _actualizoData,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 8.0),
itemCount: linea_inouthouse.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRowInOutHouse(index);
}),
),
new RefreshIndicator(
key: _RIKey3,
onRefresh: _actualizoData,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 5.0),
itemCount: linea_ocupacion.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRowOcupacion(index);
}),
),
],
),
),
),
);
}
I'd added the debugPrints and the output are 6 lines, instead of 3.
I/flutter ( 5252): [LabeledGlobalKey<RefreshIndicatorState>#4d76c]
I/flutter ( 5252): [LabeledGlobalKey<RefreshIndicatorState>#59b9e]
I/flutter ( 5252): [LabeledGlobalKey<RefreshIndicatorState>#2c88b]
I/flutter ( 5252): [LabeledGlobalKey<RefreshIndicatorState>#7bd42]
I/flutter ( 5252): [LabeledGlobalKey<RefreshIndicatorState>#1c984]
I/flutter ( 5252): [LabeledGlobalKey<RefreshIndicatorState>#dbe20]
the app works, but after changing tabs a few times, it crashes with this error:
I/flutter ( 5252): ══╡ EXCEPTION CAUGHT BY WIDGETS LIBRARY ╞═══════════════════════════════════════════════════════════
I/flutter ( 5252): The following assertion was thrown building NotificationListener<KeepAliveNotification>:
I/flutter ( 5252): Multiple widgets used the same GlobalKey.
I/flutter ( 5252): The key [LabeledGlobalKey<RefreshIndicatorState>#7bd42] was used by multiple widgets. The parents of
I/flutter ( 5252): those widgets were:
I/flutter ( 5252): - RepaintBoundary-[<[LabeledGlobalKey<RefreshIndicatorState>#7bd42]>](renderObject:
I/flutter ( 5252): RenderRepaintBoundary#60a4a DETACHED)
I/flutter ( 5252): - RepaintBoundary-[<[LabeledGlobalKey<RefreshIndicatorState>#7bd42]>](renderObject:
I/flutter ( 5252): RenderRepaintBoundary#c8cdb NEEDS-LAYOUT NEEDS-PAINT)
I/flutter ( 5252): A GlobalKey can only be specified on one widget at a time in the widget tree.
The keys are generated in the Build method, so, I don't understand why the Multiple widgets used the same GlobalKey error
Why the key is generated again, and why it's not unique? I'm not talking of a thousand intents, the error appears after changing between tabs 4 or 5 times.
Thank you for any help.
解决方案 Could you create your keys "by hand" and use static/constant values? e.g. ...
import 'package:flutter/widgets.dart';
class RIKeys {
static final riKey1 = const Key('__RIKEY1__');
static final riKey2 = const Key('__RIKEY2__');
static final riKey3 = const Key('__RIKEY3__');
}
then in ...
body: new TabBarView(
children: [
new RefreshIndicator(new RefreshIndicator(
// Use the Manual Static Value instead ...
key: RIKeys.riKey1,
onRefresh: _actualizoData,
child: new ListView.builder(
padding: new EdgeInsets.only(top: 5.0),
itemCount: linea_reservas.length * 2,
itemBuilder: (BuildContext context, int position) {
if (position.isOdd) return new Divider();
final index = position ~/ 2;
return _buildRow(index);
}),
),
I have done this in a similar situation with some success ... especially with redux or other similar patterns ...
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