CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
TheSwiftGuy77
TheSwiftGuy77

Reputation: 656

How to get all nested child's data in Firebase database?

I have a Firebase database structure below. How do I get the value of room_name_public? I want to retrieve all those values and show it in a list view. Here, 55aqdTkLPrMwB6H0KX4Z0RUe6s52 is a Firebase userID and -KcqR5Db5BidD0XpQ1z1 is created by the push() function.

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Upvotes: 3

Views: 4228

Answers (1)

Valentino
Valentino

Reputation: 2135

Ok, you can try in this way.

Create a plain object, like this:

public class Room {
    String room_name_pucblic;

    public Room() {

    }

    public Room(String room_name_pucblic) {
        this.room_name_pucblic = room_name_pucblic;
    }

    public String getRoom_name_pucblic() {
        return room_name_pucblic;
    }

    @Exclude
    public Map<String, Object> toMap() {
        HashMap<String, Object> result = new HashMap<>();
        result.put("room_name_pucblic", room_name_pucblic);

        return result;
    }
}

Next, in your activity or fragment, declare and define the listener: 

ValueEventListener roomsValueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for ( DataSnapshot userDataSnapshot : dataSnapshot.getChildren() ) {
            if (userDataSnapshot != null) {
                for ( DataSnapshot roomDataSnapshot : userDataSnapshot.getChildren() ) {
                    Room room = roomDataSnapshot.getValue(Room.class);

                    yourList.add(room.getRoom_name_pucblic());
                    yourAdapter.notifyDataSetChanged();
                }
            }
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
});

mFirebaseDatabaseReference.addListenerForSingleValueEvent(roomsValueEventListener);

I suppose that mFirebaseDatabaseReference is the firebase reference of your public_rooms node. yourList is an ArrayList of strings, connected to your adapter for the list view.

Hope this helps

Update

If you want to fetch user's rooms, knowing an userId, you have to edit the previous approach in this way:

ValueEventListener roomsValueEventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {


        for ( DataSnapshot roomDataSnapshot : dataSnapshot.getChildren() ) {
            Room room = roomDataSnapshot.getValue(Room.class);

            yourList.add(room.getRoom_name_pucblic());
            yourAdapter.notifyDataSetChanged();
        }


    }

    @Override
    public void onCancelled(DatabaseError databaseError) {

    }
});


mFirebaseDatabaseReference = FirebaseDatabase.getInstance().getReference();
mFirebaseDatabaseReference.child(userId).addListenerForSingleValueEvent(roomsValueEventListener);

Upvotes: 4

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