Getting child count in Firebase

Question

Please how do I simply get the child count from a firebase Query. For example Let's say I use a database query with 10 children, how do I get that value because I tried using onChildChanged and getting the value from the snapshot, but it does not work well. This is because at first it will get the number, then it will query again because it has to continuously sync, but because there is not actual child change at the second query it return a value if zero which will replace the original correct value. :/

   databaseReference.child("PrinterView").child(uni).child(phone).orderByChild("done").equalTo("No").addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Toast.makeText(getActivity(),"Number:"+String.valueOf(dataSnapshot.getChildrenCount()),Toast.LENGTH_LONG).show();

        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {

        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {

        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

Both don't work

   databaseReference.child("PrinterView").child(uni).child(phone).orderByChild("done").equalTo("No").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Toast.makeText(getActivity(),"Number:"+String.valueOf(dataSnapshot.getChildrenCount()),Toast.LENGTH_LONG).show();
            Vendor_view_Home_fragment.printIndicator.setText(String.valueOf(dataSnapshot.getChildrenCount()));
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

https://stackoverflow.com/a/37601712/5065318 Please refer to this answer and let me know if you get any ideas. Basically inside on child Changed you should get the child count. — vivek verma, Sep 25 '17 at 13:23
And you want to count all the childs under 5588? Is that correct? — Alex Mamo, Sep 25 '17 at 13:45
yes, but only those that have a value "done" equal to "No" as shown in one of the queries above. All the entries have a key called "done", I just want the number of those whose value of done=No , — Lemuel Ogbunude, Sep 25 '17 at 13:51
I understand. In this case please, update the database structure with the content of those childs and i will write you the code. — Alex Mamo, Sep 25 '17 at 13:54
lol.. of course I surely will. Though I suspect it's from my code. I wanna do some check up and tweak some things. — Lemuel Ogbunude, Sep 25 '17 at 14:21

Alex Mamo · Answer 1 · 2019-10-30T10:42:14.563

Assuming that PrinterView is a direct child of your Firebase root, please use the following code:

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference yourRef = rootRef.child("PrinterView").child("Covenant University").child("588");
Query query = yourRef.orderByChild("done").equalTo("No");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        long count = dataSnapshot.getChildrenCount();
        Log.d("TAG", String.valueOf(count));
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
query.addListenerForSingleValueEvent(eventListener);

So, this code works because this is what I used to find out the issue, It works, but does not solve the problem. I wrote what solves the issue below. Thanks :). — Lemuel Ogbunude, Sep 25 '17 at 14:44

Lemuel Ogbunude · Answer 2 · 2018-01-08T22:55:43.607

The problem was this line:

databaseReference.child("PrinterView").child(uni).child(phone).orderByChild("done").equalTo("No").addValueEventListener(new ValueEventListener()

The variable "uni" and "phone" was also provided by a firebase Query E.G It was to get the University and phone number of the current user so I could not just put a static string there.

    databaseReference.child("Users").child(mAuth.getCurrentUser().getUid()).child("Phone").addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            phone = dataSnapshot.getValue().toString();
            // Toast.makeText(getActivity(), phone, Toast.LENGTH_LONG).show();
            setPendingList();
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });

So the issue was that, if the network connection was slow or if the queries were not done yet, those two variables would be empty thereby making the dataSnapshot empty. I will have to sort that out by only allowing that to be queried when the rest are sure to be done. :)

Getting child count in Firebase

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