Flutter 在对话框中使用BLoC:找不到正确的提供程序

我正在尝试使用一个bloc来管理对话框的内容。我是个新手

该页面定义为：

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
      title: Text("Business Region Manager"),
    ),
    body: MultiBlocProvider(
      providers: [
        BlocProvider(
          create: (context) =>
              EntityModifyBloc(repository: widget.repository),
        ),
        BlocProvider(
          create: (context) => EntityBloc(
              repository: widget.repository,
              modifyBloc: BlocProvider.of<EntityModifyBloc>(context)),
        ),
        BlocProvider(
          create: (context) => BusinessRegionBloc(repository: widget.repository),
        ),
      ],
      child: Center(
        child: BusinessRegionPage(widget.business),
      ),
    ));
}

BusinessRegionDialog是一个有状态的小部件，状态实现构建为：

@override
Widget build(BuildContext context) {
  return BlocBuilder<BusinessRegionBloc, BusinessRegionState>(builder: (context, state) {
    if (state is BusinessRegionEmpty) {
      BlocProvider.of<BusinessRegionBloc>(context).add(GetBusinessRegions(widget.businessId));
    }
    if (state is BusinessRegionError) {
      return Center(
        child: Text('Busines Region Error'),
      );
    }
    if (state is BusinessRegionLoaded) {
      return Center(
        child: Text('BusinessRegionLoaded'),
      );
    }
    return Center(
      child: CircularProgressIndicator(),
    );
  });

所以我试着：

void onAddBusinessRegion() {
  print("OnAddCallback: " + context.hashCode.toString());
  BusinessRegionClient brClient = BusinessRegionClient(client: http.Client());
  BusinessRegionRepository brRepository =
      BusinessRegionRepository(client: brClient);

  showDialog(
    context: context,
    barrierDismissible: false,
    builder: (BuildContext context) {
      return Provider<BusinessRegionBloc>(
          create: (_) => BusinessRegionBloc(repository: brRepository),
          builder: (context) {
            return BusinessRegionDialog(
              positiveText: "Ok",
              onPositive: onPositive,
              negativeText: 'Cancel',
              onNegative: onNegative,
              businessId: widget.business.id,
            );
          });
    });
}

void onAddBusinessRegion（）{
打印（“OnAddCallback:+context.hashCode.toString（））；
BusinessRegionClient brClient=BusinessRegionClient（客户端：http.client（））；
BusinessRegionRepository brRepository=
BusinessRegionRepository（客户：brClient）；
显示对话框(
上下文：上下文，
禁止：错误，
生成器：（BuildContext上下文）{
返回提供者(
创建：（）=>BusinessRegionBloc（存储库：brRepository），
生成器：（上下文）{
返回业务区域对话(
肯定文字：“好的”，
onPositive:onPositive，
negativeText:'取消'，
否定的，否定的，
businessId:widget.business.id，
);
});
});
}

IDE告诉我： 无法将参数类型“BusinessRegionDialog Function（BuildContext）”分配给参数类型“Widget Function（BuildContext，Widget）”

---

我显然不明白什么。我所要做的就是用我的存储库中未来的信息填充一个对话框。任何指导都将不胜感激。

多亏了so条目，我终于找到了答案：

这里的答案是使用堆栈使对话框和页面共存，并在侦听器的状态正确时显示对话框。答案使用了一个无状态小部件来管理SnackBar（在答案中）。为了能够向bloc添加事件，我使用了StatefulWidget

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
    title: Text("Business Region Manager"),
    ),
    body: MultiBlocProvider(
      providers: [
        BlocProvider(
          create: (context) => EntityModifyBloc(
              repository: xbrRepository), //widget.repository),
        ),
        BlocProvider(
          create: (context) => EntityBloc(
              repository: xbrRepository, //widget.repository,
              modifyBloc: BlocProvider.of<EntityModifyBloc>(context)),
        ),
        BlocProvider(
          create: (context) => BusinessRegionDialogBloc(
              repository: xbrRepository),
        ),
      ],
      child: Stack(children: [
        BusinessRegionDialogManager(widget.business.id),
        Center(child: BusinessRegionPage(widget.business)),
      ]),
    ));
}

class BusinessRegionDialogManager extends StatefulWidget {
  final int businessId;

  BusinessRegionDialogManager(this.businessId);

  State<BusinessRegionDialogManager> createState() =>
    _BusinessRegionDialogManagerState();
}

@覆盖
小部件构建（构建上下文）{
返回脚手架(
appBar:appBar(
标题：文本（“业务区域经理”），
),
主体：MultiBlocProvider(
供应商：[
BlocProvider(
创建：（上下文）=>EntityModifyBloc(
repository:XBRepository），//widget.repository），
),
BlocProvider(
创建：（上下文）=>EntityBloc(
repository:XBRepository，//widget.repository，
modifyBloc:BlocProvider.of（上下文）），
),
BlocProvider(
创建：（上下文）=>BusinessRegionDialogBloc(
存储库：XBRepository），
),
],
子：堆栈（子：[
BusinessRegionDialogManager（widget.business.id），
中心（子：BusinessRegionPage（widget.business）），
]),
));
}
类BusinessRegionDialogManager扩展StatefulWidget{
最终int businessId；
BusinessRegionDialogManager（this.businessId）；
状态createState（）=>
_BusinessRegionDialogManagerState（）；
}

class\u businessRegionDialogManager状态 扩展状态{

// Callback functions from the dialog so can have access to
// BusinessRegionDialogBloc
void xnPositive(List<Region> addedRegions) {
    BlocProvider.of<BusinessRegionDialogBloc>(context)
      .add(AddBusinessRegions(addedRegions, widget.businessId));
}

void xnNegative(){
}


@override
Widget build(BuildContext context) {
  return BlocListener<BusinessRegionDialogBloc, BusinessRegionDialogState>(
    listener: (context, state) {
      if (state is RegionDialogLoaded) {
        showDialog(
          context: context,
          barrierDismissible: false,
          builder: (BuildContext context) {
            return BusinessRegionDialog(
              onPositive: xnPositive,
              onNegative: xnNegative,
              regions: state.regions,
            );
          })
      }
    },
    child: Container(),
  );
}

//对话框中的回调函数，以便可以访问
//商业区域DialogBloc
void xnPositive（列表添加区域）{
BlocProvider.of（上下文）
.add（AddBusinessRegions（addedRegions，widget.businessId））；
}
void xnNegative（）{
}
@凌驾
小部件构建（构建上下文）{
返回BlocListener(
侦听器：（上下文、状态）{
如果（状态为RegionDialogLoaded）{
显示对话框(
上下文：上下文，
禁止：错误，
生成器：（BuildContext上下文）{
返回业务区域对话(
onPositive:xnPositive，
否定的，否定的，
地区：州。地区，
);
})
}
},
子级：容器（），
);
}

你需要做的是创建BlocTypeA的提供者并将其传递给子对象。使用另一个context2创建一个对话框使用提供者传递bloc.value，然后使用context2构建其子对象并在子窗口小部件内使用previus上下文访问bloc。使用BlocTypeA阅读…因此我可以问题解决了

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(
    title: Text("Business Region Manager"),
    ),
    body: MultiBlocProvider(
      providers: [
        BlocProvider(
          create: (context) => EntityModifyBloc(
              repository: xbrRepository), //widget.repository),
        ),
        BlocProvider(
          create: (context) => EntityBloc(
              repository: xbrRepository, //widget.repository,
              modifyBloc: BlocProvider.of<EntityModifyBloc>(context)),
        ),
        BlocProvider(
          create: (context) => BusinessRegionDialogBloc(
              repository: xbrRepository),
        ),
      ],
      child: Stack(children: [
        BusinessRegionDialogManager(widget.business.id),
        Center(child: BusinessRegionPage(widget.business)),
      ]),
    ));
}

class BusinessRegionDialogManager extends StatefulWidget {
  final int businessId;

  BusinessRegionDialogManager(this.businessId);

  State<BusinessRegionDialogManager> createState() =>
    _BusinessRegionDialogManagerState();
}

// Callback functions from the dialog so can have access to
// BusinessRegionDialogBloc
void xnPositive(List<Region> addedRegions) {
    BlocProvider.of<BusinessRegionDialogBloc>(context)
      .add(AddBusinessRegions(addedRegions, widget.businessId));
}

void xnNegative(){
}


@override
Widget build(BuildContext context) {
  return BlocListener<BusinessRegionDialogBloc, BusinessRegionDialogState>(
    listener: (context, state) {
      if (state is RegionDialogLoaded) {
        showDialog(
          context: context,
          barrierDismissible: false,
          builder: (BuildContext context) {
            return BusinessRegionDialog(
              onPositive: xnPositive,
              onNegative: xnNegative,
              regions: state.regions,
            );
          })
      }
    },
    child: Container(),
  );
}