CODEWITHSUNDEEP
androidjsonfirebasefirebase-realtime-database
user1406716
user1406716

Reputation: 9705

Simple read of child nodes from Firebase DB not working

This is my JSON Tree in the Firebase Realtime database. I just want to iterate and read through all of the items under questions. I think I am doing something silly wrong.

Under the "My App" - I have a "questions" branch and saving a bunch of data under it. Below is the tree and my code. In the code I point out the part that is crashing. Circled in red below are what I am trying to read.

enter image description here

public void readfromFireDB() {

    FirebaseDatabase database = FirebaseDatabase.getInstance();
    DatabaseReference myRef = database.getReference().child("questions");

    // Read from the database
    myRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {

            **THIS IS THE ERROR, ques comes back as NULL**
            Question ques = dataSnapshot.getValue(Question.class);

            String key = dataSnapshot.getKey();

        }

        @Override
        public void onCancelled(DatabaseError error) {
        }
    });

}

This Issue: ques in onDataChanged() comes back as a null reference. May be I am not accessing the children under questions properly?

Upvotes: 0

Views: 440

Answers (1)

Frank van Puffelen
Frank van Puffelen

Reputation: 599216

By using a ValueEventListener you're accessing the list of questions, not an individual question.

To access each individual question, you'll need to loop over the snapshot:

public void onDataChange(DataSnapshot dataSnapshot) {
    for (DataSnapshot questionSnapshot: dataSnapshot.getChildren()) {
        Question ques = questionSnapshot.getValue(Question.class);
        String key = questionSnapshot.getKey();
    }
}

Upvotes: 2

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