Flutter / Firebase How to update Stream in StreamBuilder

Question

Hello I am developing MobileApp with Flutter and Firebase

I have a question about the Stream builder.

In my code, I am getting the data with Stream builder from Firebase, I got the date what I needed, but my question is I want to change the stream in the screen Once I press any button.

For example which is my initial stream,

gvDatabaseService.postCollectionReference
        .doc(widget.hiveCode)
        .collection('Posts')
        .snapshots()

Once I press button I want to change the stream like this

gvDatabaseService.postCollectionReference
        .doc(widget.hiveCode)
        .collection('Posts')
        .where('isOpened', isEqualTo: false)
        .snapshots()

So what I did , I declare variable named stream, in iniState I defined initial value. Also by making button that change stream with setState, I changed stream. It actually work and I got the data that I needed, however I feel it seems like bit weird. I am just wondering if which way is proper way or not..

Thanks for reading, I am waiting for your help...

class PostMainScreen extends StatefulWidget {
  final String hiveCode;
  PostMainScreen({
    Key key,
    @required this.hiveCode,
  }) : super(key: key);

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

class _PostMainScreenState extends State<PostMainScreen> {
//Variable ——————————————————————————————————
  Authentication authentication;
  var stream;
  //—————————————————————————————————— Variable

//Functions——————————————————————————————————

  @override
  void initState() {
    super.initState();
    // getSnapshot();
    stream = gvDatabaseService.postCollectionReference
        .doc(widget.hiveCode)
        .collection('Posts')
        .snapshots();
  }

  buildHeader() {
    return Container(
      height: getMQHeight(context: context) * 0.3,
      width: getMQWidth(context: context),
      color: Colors.blue,
      child: Center(
        child: InkWell(
          onTap: () {
            setState(() {
              stream = gvDatabaseService.postCollectionReference
                  .doc(widget.hiveCode)
                  .collection('Posts')
                  .where('isOpened', isEqualTo: false)
                  .snapshots();
            });
            print('here2');
          },
          child: Text('Click'),
        ),
      ),
    );
  }

  buildPostList() {
    return Expanded(
      child: Container(
          width: getMQWidth(context: context),
          color: Colors.red,
          child: StreamBuilder<QuerySnapshot>(
            stream: stream,
            builder: (context, snapshots) {
              if (!snapshots.hasData) {
                return LoadingScreen();
              } else {
                List<AnnouncementBox> annList = [];
                snapshots.data.docs.forEach((post) {
                  annList.add(AnnouncementBox(
                    post: Post.fromDocument(post),
                  ));
                });
                return ListView(
                  children: annList,
                );
              }
            },
          )),
    );
  }

  buildBody() {
    return Container(
      child: Column(
        children: [buildHeader(), buildPostList()],
      ),
    );
  }

//——————————————————————————————————Functions

  @override
  Widget build(BuildContext context) {
    authentication = Provider.of<Authentication>(context, listen: true);
    return Scaffold(
      body: buildBody(),
    );
  }
}