Return list from a child in firebase

Question

Good morning ! Guys, I have a situation in which I want to return in a list all the data whose one of the children are equal to id, in the image below I have the nodes structures of my database in firebase and I want to return for example the number of all activities whose one of the nodes (idUsuario) be the same as the logged-in user (in case I used a form of encryption to store the user id and the id I can recover normally), to improve, in a relational database would look something like this: select * from activities Where idUsuario = "A" for example;

Well, to solve this problem I changed the structure I was using to save the data in firebase so it would look like this:

This way I can bring more easily the data that is tied to the indicated user:

//Evento de consulta
    valueEventListener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            //LIMPANDO A LISTA
            atividadeArrayList.clear();

            //Listando cada uma das atividades criadas pelo usuário
            for (DataSnapshot dados: dataSnapshot.getChildren()){ //recupera os filhos do nó principal
                Atividade atividade = dados.getValue(Atividade.class);
                atividadeArrayList.add(atividade);
            }

            adapter.notifyDataSetChanged();
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    };

But thank you Matheus for your help !

Answer 1

So, the problem is that you add a "key" to the string "profile, if you always have access to this key that comes before profile, you can make a comparison in Query:

Query query = ref.orderByChild('idUsuario').equalTo('seuID');
query.addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot querySnapshot : dataSnapshot.getChildren()) {
            MyClass id = dataSnapshot.getValue(MyClass.class); // ou String id = dataSnaptshot.getValue(MyClass.class).toString();
            if (id.MyID.equals('xxxxxxxxperfil')) {
                console.log(querySnapshot.getKey());
            }
        }
    }

    @Override
    public void onCancelled(FirebaseError firebaseError) {

    }
});