Is It Possible To Update A Specific Child's Value Without Id Or Key In Firebase Realtime Database From Android On Button Click?

this is my database and now I need to change the value of favorite from 0 to 1 but I don't have any specific id so how can I change specific child's value on click in android! [ent

Solution 1:

In order to update a node, you must know the complete path to that node.

Firebase does not support the concept of update queries, where you can pass a condition to an update statement. So if you don't know the complete path, you will have to take a two-step approach:

1. Perform a query to find the node(s) to update.
2. Update each node.

Say that for example the Name property identifies the nodes you want to update, you could do that with:

DatabaseReferenceref= FirebaseDatabase.getInstance().getReference("Cameras");
Queryquery= ref.orderByChild("Name").equalTo("TheNameOfTheNodeYouWantToUpdate");
query.addListenerForSingleValueEvent(newValueEventListener() {
    @OverridepublicvoidonDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot cameraSnapshot: dataSnapshot.getChildren()) {
            cameraSnapshot.getReference().child("Favorite").set(1);
        }
    }

    @OverridepublicvoidonCancelled(DatabaseError databaseError) {
        throw databaseError.toException();
    }
}

Given that you're updating a counter in the above, you'll actually probably want to use a transaction inside that onDataChange:

DatabaseReferencefavRef= cameraSnapshot.getReference().child("Favorite");

favRef.runTransaction(newTransaction.Handler() {
    @Overridepublic Transaction.Result doTransaction(MutableData mutableData) {
        IntegercurrentValue= mutableData.getValue(Integer.class);
        if (currentValue == null) {
            mutableData.setValue(1);
        } else {
            mutableData.setValue(currentValue + 1);
        }

        return Transaction.success(mutableData);
    }

    @OverridepublicvoidonComplete(DatabaseError databaseError, boolean b,
                           DataSnapshot dataSnapshot) {
        // Transaction completed
        Log.d(TAG, "transaction:onComplete:" + databaseError);
    }
});