How to recover all data inside the key in Firebase

Question

I have this structure at Firebase. And I need to capture all the latitudes and longitudes that are inside each key, I did a test and it’s working if I put this data in a folder without the key it shows the marker on the map without problems, but just one, I want to capture and add all of them as markers on the map, How can I do it? for?

DatabaseReference ref = FirebaseDatabase.getInstance().getReference();

    ref.child("uploads").addListenerForSingleValueEvent(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            if (dataSnapshot.exists()) {

                double location_left = (dataSnapshot.child("latitude").getValue(Double.class));
                double location_right = Double.valueOf(dataSnapshot.child("longitude").getValue(Double.class));
                LatLng local = new LatLng(location_left, location_right);
                mMap.addMarker(new MarkerOptions().position(local).title("Novo Marcador"));
                mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(local, 18));
            } else {
                Log.i("MeuLOG", "erro na captura");
            }
        }

Answer 1

To solve your problem do the following:

Makes the declaration in global scope of these variables

private String nome;
private String latitude;
private String longitude;
Marker marcador;

Then just make change in your method.

DatabaseReference ref = FirebaseDatabase.getInstance().getReference();

ref.child("uploads").addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {

    if (dataSnapshot.exists()) {

        for (DataSnapshot s : dataSnapshot.getChildren()) {

            nome = s.child("nome").getValue().toString();
            latitude = s.child("latitude").getValue().toString();
            longitude = s.child("longitude").getValue().toString();
            LatLng zoom = new LatLng(Double.valueOf(latitude), Double.valueOf(longitude));

            marcador = mMap.addMarker(new MarkerOptions()
                            .position(new LatLng(Double.valueOf(latitude), Double.valueOf(longitude)))
                            .title(nome));

            mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(zoom, 18));

            } 
        } else {
            Log.i("MeuLOG", "erro na captura");
        }

    }
}

This function in addition to traversing each id of its database contained in upload to collect the latitudes and longitudes, will also insert into your bookmark nomes if in the database.

I have a project that works with mapas and Firebase.

Answer 2

Try it this way:

DatabaseReference ref = FirebaseDatabase.getInstance().getReference("uploads");

    ValueEventListener listener = new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            Postagem.removeAll(Postagem);
            for (DataSnapshot single: dataSnapshot.getChildren()){

                if (single.exists()) {

                        double location_left = (single.child("latitude").getValue(Double.class));
                        double location_right = Double.valueOf(single.child("longitude").getValue(Double.class));
                        LatLng local = new LatLng(location_left, location_right);
                        mMap.addMarker(new MarkerOptions().position(local).title("Novo Marcador"));
                        mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(local, 18));
                } else {
                    Log.i("MeuLOG", "erro na captura");
                }
            }
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    };
    ref.addValueEventListener(listener);

Answer 3

Try the following

DatabaseReference ref = FirebaseDatabase.getInstance().getReference();

ref.child("uploads").addValueEventListener(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        if (dataSnapshot.exists()) {
            for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                double location_left = postSnapshot.child("latitude").getValue(Double.class);
                // resto do codigo
            }
        } else {
            Log.i("MeuLOG", "erro na captura");
        }
    }
}

A little short of time to explain what the code does exactly, but basically it goes through your Ode with the logic that was applied, using a for. I used the addValueEventListener so that you can go through all the items instead of just one. You get the whole Node uploads and you’ll be able to go through his data.