BLoC模式的Flutter Firestore错误

Question

A newbie in flutter has a lot of stuff that is just starting to figure out now it's BLoC pattern and now I ran into a problem I can not understand how to fix this error, seems to have written everything correctly Here generic Interface for all BLoCs

abstract class BlocBase {
  void dispose();
}

class BlocProvider<T extends BlocBase> extends StatefulWidget {
  BlocProvider({
    Key key,
    @required this.child,
    @required this.bloc,
  }) : super(key: key);

  final T bloc;
  final Widget child;

  @override
  _BlocProviderState<T> createState() => _BlocProviderState<T>();

  static T of<T extends BlocBase>(BuildContext context) {
    final type = _typeOf<BlocProvider<T>>();
    BlocProvider<T> provider = context.ancestorWidgetOfExactType(type);
    return provider.bloc;
  }

  static Type _typeOf<T>() => T;
}

class _BlocProviderState<T> extends State<BlocProvider<BlocBase>> {
  @override 
  void dispose() {
    widget.bloc.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return widget.child;
  }
}

Here is the second file in which I use BLoC and where it gives an error Here I use function validateAndCreateData through which I add Tickets

@override
  Widget build(BuildContext context) {
    final bloc = BlocProvider.of<TicketsBloc>(context);
    return Scaffold(
        drawer: MyDrawer(),
        appBar: AppBar(
            title: Text('Sports'),
            backgroundColor: Colors.blueGrey[900],
            // automaticallyImplyLeading: false,
            actions: <Widget>[
              IconButton(
                  icon: Icon(Icons.share),
                  tooltip: 'Share',
                  onPressed: () {
                    Navigator.of(context).pushNamed('/second_screen');
                  }),
              IconButton(
                  icon: Icon(Icons.account_circle),
                  tooltip: 'Your account',
                  onPressed: () {
                    Navigator.of(context)
                        .pushReplacementNamed('/account_screen');
                  }),
              IconButton(
                icon: Icon(Icons.add),
                tooltip: 'Add Tickets',
                onPressed: () => validateAndCreateData(bloc),
              )
            ]),
        body: MyTab(),
    );
  }
void validateAndCreateData(TicketsBloc bloc) async {
      bloc.createData(description, image, name, price);

  }

Answer 1

Your error mean you don't have access to the bloc. You must wrap your app with the provider. If not you cannot inherited from this.

return BlocProvider(
    child: MaterialApp(
      title: 'My App',
      home: HomeScreen(),
  ),
);