datastore + pigeon

1- pigeon.dart

@datastore
class Profile {
  String name;
  String address;
  Image profile;
}

@HostApi
abstract class ProfileApi {
  Profile getProfile();
}

@datastore
class FeedList {
  String topic;
  List<FeedItem> items;
}

@datastore
class FeedItem {
  String timestmap;
  String title;
  String summary;
}

@FlutterApi
abstract class FeedApi {
  void displayNewsFeed(FeedList feedList);
}

2- profile.dart

// Flutter gets an observable Profile

class ProfileWidget extends StatefulWidget {
  ProfileWidget({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _ProfileWidgetState createState() => _ProfileWidgetState();
}


class _ProfileWidgetState extends State<ProfileWidget> implements ProfileApiHandler {
  // This is observable.
  ValueNotifier<Profile> profile;

  @override
  void initState() {
    super.initState();
    ProfileApi().getProfile().then((ValueNotifier<Profile> profile) {
      setState(() {
        this.profile = profile
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: ValueListenableBuilder(
          builder: (BuildContext context, Profile profileSnapshot, Widget? child) {
            return // Do stuff;
          },
          valueListenable: profile,
        ),
      ),
    );
  }
}

3- feed.dart

// Flutter gets pushed an observable feed list with observable feed items

class FeedWidget extends StatefulWidget {
  FeedWidget({Key key, this.title}) : super(key: key);

  final String title;

  @override
  _FeedWidgetState createState() => _FeedWidgetState();
}


class _FeedWidgetState extends State<FeedWidget> implements FeedApiHandler {
  // This is observable.
  ValueNotifier<FeedList> feedList;

  @override
  void initState() {
    super.initState();
    FeedApi.setup(this);
  }

  // Does this support our previous platform channel buffer work?
  void displayNewsFeed(ValueNotifier<FeedList> feedList) {
    setState(() => this.feedList = feedList);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: ValueListenableBuilder(
          builder: (BuildContext context, FeedList feedList, Widget? child) {
            return GridView.count(
              crossAxisCount: 2,
              children: List.generate(feedList.items.count, (index) {
                return FeedItemWidget(feedList.items[index]);
              }),
            );
          },
          valueListenable: feedList,
        ),
      ),
    );
  }
}

class FeedItemWidget extends StatelessWidget {
  final ValueNotifier<FeedItem> feedItem;

  FeedItemWidget(this.feedItem);

  @override
  Widget build(BuildContext context) {
    return ValueListenableBuilder(
      builder: (BuildContext context, FeedItem item, Widget? child) {
        return // Do things
      },
      valueListenable: feedItem,
    );
  }
}