clean_architecture_dane_comments.dart

class Comments extends StatelessWidget {
  final int postId;
  Comments(this.postId);

  @override
  Widget build(BuildContext context) {
    return Injector(
      //NOTE1: Inject CommentsService
      inject: [Inject(() => CommentsService(api: Injector.get()))],
      builder: (context) {

        return StateBuilder(
          models: [Injector.getAsReactive<CommentsService>()],
          //NOTE2: fetch comments in the init state
          initState: (_, commentsServiceRM) => commentsServiceRM.setState(
            (state) => state.fetchComments(postId),
            //NOTE3: Delegate to ErrorHandler class to show an alert dialog
            onError: ErrorHandler.showErrorDialog,
          ),
          builder: (_, commentsServiceRM) {
            //NOTE4 use whenConnectionState
            return commentsServiceRM.whenConnectionState(
              onIdle: () =>
                  Container(), //Not reachable because setState is called form initState
              onWaiting: () => Center(child: CircularProgressIndicator()),
              onData: (state) => Expanded(
                child: ListView(
                  children: state.comments
                      .map((comment) => CommentItem(comment))
                      .toList(),
                ),
              ),
              //NOTE4: Display empty container on error. An AlertDialog should be displayed
              onError: (_) => Container(),
            );
          },
        );
      },
    );
  }
}