如何删除 firebase 数据库中的整个关键数据？

Question

I making an app using Firebase. Structure of my data storage is-

I am calling subject and description in another activity to show them. I added a button in that activity which delete that particular key(-L6g7ttOxr... highlighted portion) data shown in Image above. I successfully got that key in second activity for particular list item to give database reference.

public void deleteCurrentMemo(){
    AlertDialog.Builder alert = new AlertDialog.Builder(
            DisplayMemo.this);
    alert.setTitle("Delete Memo");
    alert.setMessage("Are you sure you want delete current Memo?");
    Toast.makeText(this,key,Toast.LENGTH_SHORT).show();
    alert.setPositiveButton("Yes", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            mFirebaseDatabase = FirebaseDatabase.getInstance();
            mMemoDatabaseReference = mFirebaseDatabase.getReference().child("memos").child(key);
            mMemoDatabaseReference.removeValue();
            finish();
        }
    });
    alert.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            dialog.dismiss();
        }
    });
    alert.show();
}

Above code is in second activity called on delete Button. Now how can I delete complete key data?

Answer 1

You will need to pass the key of the memo to the second activity.

Typically this is quite easy, since you already get the key when you read the data from Firebase. Just pass is along with the subject and subscription to the second activity, and then into deleteCurrentMemo .

Answer 2

By this way i have successfully delete child node.

N:B You must need key of your node that you want to delete.

    database.getReference().child("Groups").child(groupItem.getGroupkey()).removeValue().addOnSuccessListener(new OnSuccessListener<Void>() {
                    @Override
                    public void onSuccess(Void aVoid) {
                        new CustomMessage(GroupDetailsActivity.this, "Successfully deleted");
                    }
                }).addOnFailureListener(new OnFailureListener() {
                    @Override
                    public void onFailure(@NonNull Exception e) {
                        Customlog.showlogD("ERROR_MSG",e.getMessage());
                    }
                })

;