上下文不包含块

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在以下测试代码中，当单击应用程序栏中的按钮时，我试图将事件发送到TestBloc.我将BlocBuilder向外移动到支架周围.但是，当调用_reloadData方法时，会弹出以下错误

in the following test code, I am trying to send an event to the TestBloc, when a button in the app bar is clicked. I moved the BlocBuilder outwards around the scaffold. But when the _reloadData method is called, then the following error pops up

"BlocProvider.of() called with a context that does not contain a Bloc/Cubit of type TestBloc"

代码

class _TestPageState extends State<TestPage> with UiPresenter { @override Widget build(BuildContext context) { return BlocProvider( create: (context) => sl<TestBloc>()..add(GetDataEvent()), child: Scaffold( appBar: AppBar( title: AppBarTitleWidget( title: 'Test', onRefreshPressed: () => _reloadData(context), )), drawer: MainMenuDrawer(), body: ContentContainer( header: Text( 'Test', style: Theme.of(context).textTheme.headline1, ), child: _buildBody(context), ), ), ); } _reloadData(BuildContext context) { BlocProvider.of<TestBloc>(context).add(GetDataEvent()); }

推荐答案

您可以在下复制粘贴运行完整代码我使用以下完整代码来模拟这种情况您可以使用 Builder 包装 AppBarTitleWidget 代码段

appBar: AppBar(title: Builder(builder: (BuildContext context) { return AppBarTitleWidget( title: "Test", onRefreshPressed: () => _reloadData(context), ); }))

工作演示

完整代码

import 'package:bloc/bloc.dart'; import 'package:flutter/material.dart'; import 'package:flutter_bloc/flutter_bloc.dart'; class TestBloc extends Cubit<int> { /// {@macro counter_cubit} TestBloc() : super(0); /// Add 1 to the current state. void GetDataEvent() => emit(state + 1); /// Subtract 1 from the current state. void decrement() => emit(state - 1); } /*class CounterPage extends StatelessWidget { /// {@macro counter_page} const CounterPage({Key key}) : super(key: key); @override Widget build(BuildContext context) { return BlocProvider( create: (_) => CounterCubit(), child: CounterView(), ); } }*/ /// {@template counter_observer} /// [BlocObserver] for the counter application which /// observes all [Cubit] state changes. /// {@endtemplate} class CounterObserver extends BlocObserver { @override void onChange(Cubit cubit, Change change) { print('${cubit.runtimeType} $change'); super.onChange(cubit, change); } } void main() { Bloc.observer = CounterObserver(); runApp(CounterApp()); } class CounterApp extends MaterialApp { /// {@macro counter_app} CounterApp({Key key}) : super(key: key, home: TestPage()); } _reloadData(BuildContext context) { BlocProvider.of<TestBloc>(context).GetDataEvent(); } class TestPage extends StatefulWidget { @override _TestPageState createState() => _TestPageState(); } class _TestPageState extends State<TestPage> { @override Widget build(BuildContext context) { final textTheme = Theme.of(context).textTheme; return BlocProvider( create: (_) => TestBloc(), child: Scaffold( appBar: AppBar(title: Builder(builder: (BuildContext context) { return AppBarTitleWidget( title: "Test", onRefreshPressed: () => _reloadData(context), ); })), body: Center( child: BlocBuilder<TestBloc, int>( builder: (context, state) { return Text('$state', style: textTheme.headline2); }, ), ), floatingActionButton: Column( mainAxisAlignment: MainAxisAlignment.end, crossAxisAlignment: CrossAxisAlignment.end, children: <Widget>[ FloatingActionButton( key: const Key('counterView_increment_floatingActionButton'), child: const Icon(Icons.add), onPressed: () => context.read<TestBloc>().GetDataEvent(), ), const SizedBox(height: 8), FloatingActionButton( key: const Key('counterView_decrement_floatingActionButton'), child: const Icon(Icons.remove), onPressed: () => context.read<TestBloc>().decrement(), ), ], ), ), ); } } class AppBarTitleWidget extends StatelessWidget { final String title; final VoidCallback onRefreshPressed; const AppBarTitleWidget({ Key key, this.title, this.onRefreshPressed, }) : super(key: key); @override Widget build(BuildContext context) { return InkWell( onTap: () { onRefreshPressed(); }, child: Text(title)); } }