CODEWITHSUNDEEP
androidfirebasefirebase-realtime-database
Frreshia
Frreshia

Reputation: 11

Cant delete a child from firebase even though I can retrieve it

I built an application where I interact with firebase db. The structure is following.

game
 question
 -KiwYrNcX6B-VSLV8OmQ
   titleofquestion
    a: 
    "test"
    b: 
    "test"
    c: 
    "test"

Now to get my question object I did the following successfully.

 databaseReference = FirebaseDatabase.getInstance().getReference().child("question");
        databaseReference.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
                    Question q = postSnapshot.getValue(Question.class);
                        listValues.add(q.getA()); 
                        keyValues.add(postSnapshot.getKey()); //This gives me the titleofquestion as a string.
                        Log.d(TAG, "keyValue: "+postSnapshot.getKey());
                }
            }

When I try to use this value to delete an entry in an another method 

   databaseReference.child(keyValues.get(position)).removeValue(); //
keyValues.get(position) gives me title of question

nothing happens.How can I fix this?

Edit: I think I should use listener for the remove operation as well but I am not sure

Upvotes: 0

Views: 918

Answers (2)

Frank van Puffelen
Frank van Puffelen

Reputation: 599716

Your code boils down to:

databaseReference = FirebaseDatabase.getInstance().getReference().child("question");
keyValues.get(position) gives me title of question
databaseReference.child(keyValues.get(position)).removeValue(); //

So you're deleting the value at path: /question/<titleofquestion>.

Your JSON structure does not match this path, because you have a push ID in there: /question/<pushid>/<titleofquestion>. So the code you have (successfully) deletes a non-existing value.

I can think of two solutions:

  1. don't use a push ID
  2. store the path to the question, instead of just the key

From the JSON you shared we can't see why you have the level with the push ID in there. If that is not strictly needed, you can simplify the data model to:

game
 question
   titleofquestion
    a: 
    "test"
    b: 
    "test"
    c: 
    "test"

And then your current code will already work.

If the push ID is needed in the data model, you will the entire path of each question in order to delete it.

So first you store the entire path instead of just the key:

databaseReference = FirebaseDatabase.getInstance().getReference().child("question");
databaseReference.addChildEventListener(new ChildEventListener() {
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {
        for (DataSnapshot postSnapshot : dataSnapshot.getChildren()) {
            Question q = postSnapshot.getValue(Question.class);
                listValues.add(q.getA()); 
                keyValues.add(dataSnapshot.getKey()+"/"+postSnapshot.getKey()); //This gives the path to the question
        }
    }

And then you can delete the question with your current code:

databaseReference.child(keyValues.get(position)).removeValue();
keyValues.get(position) gives the path of question

Upvotes: 0

Gajendra Singh Rathore
Gajendra Singh Rathore

Reputation: 73

databaseReference.child(keyValues.get(position)).setValue("");

may be this, by setting the value of the key to ("") i.e. empty

Upvotes: 1

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