How can i dispose or close a listen function from Firestore?

Question

Flutter

i have this listen function into stful which i need to close it when press on the back button

    class Test extends StatefulWidget {
      const Test({Key key}) : super(key: key);
    
      @override
      _TestState createState() => _TestState();
    }
    
    class _TestState extends State<Test> {
    
      handleDelete(){
    
        FirebaseFirestore.instance.collection("handleCountM").limit(1).snapshots().listen((value) {
          value.docs.forEach((element) {
            element.reference.delete();
          });
        });

  }

  @override
  Widget build(BuildContext context) {
    return Container();
  }
}

i have no idea how could i stop it into dispose()

Solution

Stream<QuerySnapshot<Map<String, dynamic>>> myStream = FirebaseFirestore.instance.collection("handleCountM").limit(1).snapshots();

late StreamSubscription<QuerySnapshot<Map<String, dynamic>>> streamSubscription;
  

void handleDelete() {
    streamSubscription = myStream.listen((value) {
      value.docs.forEach((element) {
        element.reference.delete();
      });
    });
  }


  @override
  void dispose() {
    streamSubscription.cancel(); //Cancel your subscription here.
    super.dispose();
  }

Your other alternative, would be to use a streambuilder, and it'll handle the subscription and termination for you.

Comments

[Jack]

thanks a lot huthaifa but i don't use null safety version what should i use instead late?

[Huthaifa Muayyad]

Just remove the word late.

[Huthaifa Muayyad]

And read about null safety and start using it :) Lot's of work by the team was put into it, for many very good reasons, which are worth diving into :)