使用不包含 Bloc 类型的上下文调用 BlocProvider.of()

Question

@override
  Widget build(BuildContext context) {
    return MultiBlocProvider(
    providers: [
         BlocProvider<TripDetailBloc>(create: (BuildContext context) => TripDetailBloc()),
         BlocProvider<PopUpBloc>(create: (BuildContext context) => PopUpBloc()),
               ],
    child: Scaffold(
      floatingActionButton: FloatingActionButton(
        child: Icon(Icons.add),
        onPressed: () {
          BlocProvider.of<TripDetailBloc>(context).add(AddTripDetailPannelEvent());
        },
      ),
      appBar: appbar(),
      body: pannel(),
    )
    );
  }

The following assertion was thrown while handling a gesture:

• BlocProvider.of() called with a context that does not contain a Bloc of type TripDetailBloc.
• No ancestor could be found starting from the context that was passed to BlocProvider.of <TripDetailBloc>() .
• This can happen if the context you used comes from a widget above the BlocProvider.
• he context used was: TripDetailPage(dependencies: [MediaQuery], state: _TripDetailPageState#d4ab3)

Answer 1

Change your code to this:

Widget build(BuildContext context) {
  
  return MultiBlocProvider(
      providers: [
        BlocProvider<TripDetailBloc>(create: (BuildContext context) => TripDetailBloc()),
        BlocProvider<PopUpBloc>(create: (BuildContext context) => PopUpBloc()),
      ],
      child: Builder(
        builder: (context) {
          return Scaffold(
            floatingActionButton: FloatingActionButton(
              child: Icon(Icons.add),
              onPressed: () {
                BlocProvider.of<TripDetailBloc>(context).add(AddTripDetailPannelEvent());
              },
            ),
            appBar: appbar(),
            body: pannel(),
          );
        }
      )
  );
}

If you look closely, I have rapped your Scaffold into a widget builder.

Answer 2

Wrap your scaffold in a builder widget and use that context. The context the.of(context) is using is the same of the method build(BuildContext context), that's why it doesn't find it