RxJava with Firebase Remove child events - firebase

Question

I'm using firebase to store my data and it is structured this way:
users {
userid {information here}
}
friends {
userid {
friendid1:true
friendid2:true
}
}
If a friendid is added or removed, then an appropriate event should be called.
If the user information is changed, then an event update should be triggered.
So far I have:
RxFirebaseDatabase.observeFriendList(/*Path to friends id list*/)
.flatMap(new Func1<RxFirebaseChildEvent, Observable<User>>() {
#Override
public Observable<User> call(RxFirebaseChildEvent stringBooleanPair) {
//This is a childeventlistener callback
//The key of RxFirebaseChildEvent is the friendid
switch (stringBooleanPair.getEventType()) {
case ADDED:
return RxFirebaseDatabase.observeUserInformation(/*path to user list*/.child(stringBooleanPair.getKey()), User.class);
case REMOVED:
return null; //What do I do here to unregister the listener?
}
}
}).subscribe(user -> {
//This is a ValueEventListener callback that returns the user
//Add, remove or update here, how?
});
How do I remove the specific user listener when a friendId is removed and also call add/remove/update on that user to update the view?

Answer 1

I came up with a somewhat hacked-together version, would love to see a better implementation though.
//refUsers is path to users
List<String> userKeys = new ArrayList<>();
RxFirebaseDatabase.observeFriendList(/*Path to friends id list*/)
.flatMap(new Func1<RxFirebaseChildEvent, Observable<User>>() {
#Override
public Observable<User> call(RxFirebaseChildEvent stringBooleanPair) {
//This is a childeventlistener callback
//The key of RxFirebaseChildEvent is the friendid
switch (stringBooleanPair.getEventType()) {
case ADDED:
userKeys.add(stringBooleanPair.getKey());//User Key
return RxFirebaseDatabase
.observeUserInformation(refUsers.child(stringBooleanPair.getKey()),
User.class,
Eventype.ADDED)
.takeWhile((user) -> userKeys.contains(user.getKey()));
case REMOVED:
userKeys.remove(userid);
return RxFirebaseDatabase
.observeUserInformation(refUsers.child(userid),
User.class,
Const.EventType.REMOVED)
.take(1);
}
}
}).subscribe(userEvent -> {
//Returns an object that contains the user and the eventype (added, updated or removed)
});
Basically, I'm keeping track of the users that are in the friends list and only returning an event if the userid is still watched.

Answer 2

You don't need to do that RxFirebase library already remove your listener when you unsubscribe your Observable, you can see it if you check the implementation:
subscriber.add(Subscriptions.create(new Action0() {
#Override
public void call() {
query.removeEventListener(childEventListener);
}
I suggest you to check as reference(or just use it) my RxJava2 library if you want to update your app from RxJava to RxJava2:
https://github.com/FrangSierra/Rx2Firebase
If you are interested of it, you can see the differences between both RxJava here.