return StreamBuilder<QuerySnapshot>(
      stream: communityBloc.feedStream,
      builder: (context, AsyncSnapshot<QuerySnapshot> snapshot) {
        if (snapshot.hasError) {
          debugPrint('Snapshot error: ${snapshot.error}');
          return Text('error');
        }
        if (snapshot.connectionState == ConnectionState.none)
          return Text('stream is null, connection = none');
        if (snapshot.connectionState == ConnectionState.waiting)
          return UIUtils.Spinner();
        if (snapshot.data == null || snapshot.data.documents.length == 0) {
          return Text('no data');
        }
        return Provider(
          builder: (_) => ActivityPreviewBloc(
              Provider.of<AuthenticationBloc>(context).authenticatedUserUID),
          dispose: (_, bloc) => bloc.dispose(),
          child: ListView.builder(
            addAutomaticKeepAlives: true, // TODO review this
            itemBuilder: (context, index) => ActivityPreview(
              Activity.fromJson(
                Provider.of<GlobalBloc>(context),
                snapshot.data.documents[index].data
                  ..addEntries([
                    MapEntry(
                      'activity_id',
                      snapshot.data.documents[index].documentID,
                    )
                  ]),
              ),
            ),
            itemCount: snapshot.data.documents.length,
          ),
        );
      },
    );


Stream<QuerySnapshot> get feedStream {
    Stream<QuerySnapshot> activities = _firestore
        .collection('activities')
        .orderBy('timestamp', descending: true)
        .snapshots();
    return activities;
  }