How to delete from firebase realtime database?

Question

I am using Firebase realtime database in Android app, and have data like this:

How can i delete the record "Apple" (marked in picture)?

According to the docs, to remove an item you call removeValue() on the reference. But to get the reference i require the child id. Because its a random generated id (-KISNx87aYigsH3ILp0D), how to delete it?

thanks to both for asking and answering #Amit & @Frank van Puffelen — Däñish Shärmà, Dec 02 '16 at 06:49

Frank van Puffelen · Accepted Answer · 2017-04-29T14:16:32.237

86

If you don't know the key of the items to remove, you will first need to query the database to determine those keys:

DatabaseReference ref = FirebaseDatabase.getInstance().getReference();
Query applesQuery = ref.child("firebase-test").orderByChild("title").equalTo("Apple");

applesQuery.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for (DataSnapshot appleSnapshot: dataSnapshot.getChildren()) {
            appleSnapshot.getRef().removeValue();
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        Log.e(TAG, "onCancelled", databaseError.toException());
    }
});

edited Apr 29 '17 at 14:16

answered May 23 '16 at 14:26

Frank van Puffelen

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Thanks a lot. This is exactly what i was looking for. – Amit Jayant May 24 '16 at 11:43
why i can't find `DatabaseReference`? – R Besar Oct 06 '16 at 08:49
4

what if there are multiple nodes with title "Apple" ? – Sumit Jha Jan 30 '17 at 04:29
1

I think, you wrote that part getInstance().ref() accidently. That code should be FirebaseDatabase.getInstance().getReference(); – Yunus Haznedar Apr 29 '17 at 10:34
1

Good catch, fixed. – Frank van Puffelen Apr 29 '17 at 14:16
@FrankvanPuffelen if i want to get this object which has apple in it then what should i do in this onDataChanged method – Umair Feb 25 '18 at 11:53
@SumitJha either you limit query to first/last or any other depending upon your case or handle via your login in onDataChange – Shubham AgaRwal Jun 14 '18 at 09:57

score 16 · Answer 2 · answered Sep 23 '18 at 00:09

16

this solved my problem

 mPostReference = FirebaseDatabase.getInstance().getReference()
                        .child("quotes").child(mPostKey);
                mPostReference.removeValue();

answered Sep 23 '18 at 00:09

masokaya

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score 7 · Answer 3 · edited May 09 '19 at 18:43

7

If you are using firebase-admin you can simply try this out as

admin.ref(`/users/${userid}`).remove()

and that works for me.

And also do remember to use async and await syntax.

edited May 09 '19 at 18:43

Vlad

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answered May 09 '19 at 18:29

Debdut Saha

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score 6 · Answer 4 · edited Aug 07 '19 at 11:08

6

You can use this code :

onDeletePost(id:string){
return this.http.delete(`https://my-angular8-prjt.firebaseio.com/posts/${id}.json`).subscribe();
}

edited Aug 07 '19 at 11:08

Mohammad Reza Shahrestani

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answered Aug 07 '19 at 09:23

Amruta Goyal

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You should include details of what your answer does – clubby789 Aug 07 '19 at 09:43

score 2 · Answer 5 · answered May 23 '16 at 13:36

Depending on how and why you are deleting the data you can use these:

// Could store the push key or get it after push
String newPostKey = yourDatabase.child('firebase-test').push({
    something:something
}).key();

// Depends how you get to here
howYouGotHereId.parent().setValue(null);

Firebase Save Data 3.0

score 0 · Answer 6 · answered Feb 19 '21 at 08:38

Assume that images is the directory of your firebase database which you want to clear.

private static DatabaseReference mDatabase;
public static void clearData(){
    mDatabase = FirebaseDatabase.getInstance().getReference();
    mDatabase.child("images").setValue(null);
}

Here images is the parent directory of the database. If you want to clear a nested directory (DCIM) inside the images directory so that you can retain the remaining data in it.

In that scenario you can do like this,

mDatabase = FirebaseDatabase.getInstance().getReference();
mDatabase.child("images").child("DCIM").setValue(null);

As a response to the query, Please try to use setValue method with null value setValue(null) to clear the data from firebase database

score 0 · Answer 7 · answered Jun 19 '22 at 22:39

In the case of Firebase admin with python though:

import firebase_admin
from firebase_admin import credentials
from firebase_admin import db
cred = credentials.Certificate("<your certificate>.json")
firebase_admin.initialize_app(cred, {'databaseURL': 'https://<your db>.firebaseio.com/'})

snapshot = db.reference('firebase-test').get()
for k,v in snapshot.items():
    if v['title'] == "Apple":
        db.reference('firebase-test').child(k).delete()

How to delete from firebase realtime database?

7 Answers7

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