Contents
The provider pattern permits to widgets lower in the tree hierarchy to have access to data in the provided class.
Here, we’ll continue the example started with the Bloc pattern, and use this pattern in order to create a bloc provider.
class BlocProvider<T extends BlocBase> extends StatefulWidget {
final T bloc;
final Widget child;
const BlocProvider({Key key, @required this.bloc, @required this.child})
: super(key: key);
@override
_BlocProviderState<T> createState() => _BlocProviderState<T>();
static T of<T extends BlocBase>(BuildContext context) {
BlocProvider<T> provider =
context.findAncestorWidgetOfExactType<BlocProvider<T>>();
return provider.bloc;
}
}
class _BlocProviderState<T> extends State<BlocProvider<BlocBase>> {
@override
Widget build(BuildContext context) {
return widget.child;
}
@override
void dispose() {
widget.bloc.dispose();
super.dispose();
}
}
When we integrate the above code, we can then use the BlocProvider class as a wrapper for a widget in our tree hierarchy, and then, each of its descendants will have access to the bloc specified as the bloc argument.
For instance, we can use it like this:
BlocProvider(
bloc: EntriesBloc(),
child: MyWidgetHierarchy(
// ...
)
)
So all the children of MyWidgetHierarchy will be able to access EntriesBloc by doing this:
var bloc = BlocProvider.of<EntriesBloc>(context);
So afterwards, if we want to add an entry to the infoEntries, we just have to call
bloc.inAddEntry.add(InfoEntry());