How to delete firebase data after "n" days

Question

I want do delete some old data from my Firebase, and I have a hard time do make it work.

I tried this solution found here: Firebase chat - removing old messages

but this isn't deprecated.

so I try it this way:

ChildEventListener childEventListener = new ChildEventListener() {
    @Override
    public void onChildAdded(DataSnapshot dataSnapshot, String s) {

        Calendar calendar = Calendar.getInstance();
        calendar.add(Calendar.DAY_OF_MONTH, -30);

        Log.d(TAG, "onChildAdded:" + dataSnapshot.getKey());

        String key = dataSnapshot.getKey();

        Marker retrievemarker =dataSnapshot.getValue(Marker.class);
        Calendar t3 = new           
        GregorianCalendar
        (c.get(Calendar.YEAR),
         c.get(Calendar.MONTH),
         retrievemarker.getSavedate());

        int date1= calendar.get(Calendar.DATE);
        int date2= t3.get(Calendar.DATE);

        Log.d("date1",""+date1);
        Log.d("date2",""+date2);

        if( date1 == date2 ){

            myRef.child(key).setValue(null);

        }

for explanation: In my Firebase I save a object named Marker, this object got a variable to store the savedate, the date where the object was saved in the Firebase.

int date = c.get(Calendar.DATE);
marker.setSavedate(date);

I want to delete the object in the Firebase after 30 days. So I try to subtract 30 days from the Date Today than i want to compare this with the savedate from the Object if it equals i will delete the object from the Firebase.

For the Subtraction I refer to an answer from the following question: How to subtract X days from a date using Java calendar?

But it doesn´t work. If I add a Object today to the Firebase the two dates are always equal. So I guess the subtraction doesn´t work.

What am I doing wrong?

Frank van Puffelen · Accepted Answer · 2017-09-20T07:03:45.647

22

Say that you have a data structure with nodes line this:

-KItqNxLqzQoLnUCb9sJaddclose
  time: "Thu Apr 28 17:12:05 PDT 2016"
  timestamp: 1461888725444

Each such node has a timestamp property that indicates when it was created. Preferably you'd set this property using Server Timestamp.

With this data structure, you can easily build a query that returns only the items older than 30 days and removes them:

long cutoff = new Date().getTime() - TimeUnit.MILLISECONDS.convert(30, TimeUnit.DAYS);
Query oldItems = ttlRef.orderByChild("timestamp").endAt(cutoff);
oldItems.addListenerForSingleValueEvent(new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot snapshot) {
        for (DataSnapshot itemSnapshot: snapshot.getChildren()) {
            itemSnapshot.getRef().removeValue();
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {
        throw databaseError.toException();
    }
});

edited Sep 20 '17 at 07:03

answered May 29 '16 at 00:19

Frank van Puffelen

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Thank you for this smart solution, it help me alot. Well just for the sake of clarity and for other users who would like to do the same like me. I guess it must be +30 not -30 because minus plus minus equals plus. – worl44 May 30 '16 at 11:14
Good catch, fixed. – Frank van Puffelen May 30 '16 at 14:42
5

What if one wants to delete the data from firebase database once its older than 30 days? – Srujan Barai Apr 09 '17 at 07:57

score 1 · Answer 2 · edited Nov 23 '17 at 00:16

1

My Firebase structure is like -> firebaseurl.com/test/user_id/2017-05-12 and then my data is structured with time So I am using

long cutoff = new Date().getTime()-TimeUnit.MILLISECONDS.convert(10, TimeUnit.DAYS);

//Get days number for delete data
Date d = new Date(cutoff );
SimpleDateFormat dateFormatGmt = new SimpleDateFormat("yyyy-MM-dd");
String old_date = `dateFormatGmt.format(new Date(cutoff));

// Get date of deleting content
ref2 = new Firebase("firebaseurl.com/test/user_id/" + user_id);    // Firebase url
ref2.child(old_date).removeValue();    //Remove element

It works for me

edited Nov 23 '17 at 00:16

Sachin Jain

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answered May 12 '17 at 17:11

Ashish Sahu

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2

Hi, thank you for your contribution. Could you edit this post using [this page for help on syntax](https://stackoverflow.com/help/formatting), to make it more readable? – Hugues M. May 12 '17 at 19:41

score 0 · Answer 3 · answered Aug 12 '20 at 17:09

Another option is use PubSub google cloud with Schedule Functions from firebase, i'm using and i read documents all days (every day box) and i verify, if the date (registered on create document) is > that Today date, then, i must delete the document from firestore since it;

How to delete firebase data after "n" days

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