Deleting Firebase data after a certain time

Question

I've been trying to make this work from

How to delete firebase data after "n" days

but it's not working for me.

Here's what I'm doing,

In my "A" activity, I have a button that will save this chunk of data, with a 'timeStamp' child which holds the timestamp value. (.setValue(ServerValue.TIMESTAMP);)

After pressing the button, it saves the data successfully. Then, it starts the next activity, where we wait.

But instead of deleting after '30' days, it deletes it straight away.

I have a method that works exactly like the answer by Frank

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

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

But it's not deleting it after some time, as soon as it is posted.

Thank you.

EDIT:

data

When I run the code you posted, it behaves as expected. Export and post a slice of your database that shows the structure and timestamp values. — Bob Snyder, Dec 23 '16 at 22:33
@qbix thank you, I put a picture of my data in the question above under EDIT. — SaltySea, Dec 23 '16 at 23:18
I suspect reference `mDatabase` is not set correctly. Post the code that defines it. — Bob Snyder, Dec 23 '16 at 23:28
@qbix private DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference(); as a global variable — SaltySea, Dec 23 '16 at 23:47

score 1 · Accepted Answer · answered Dec 23 '16 at 23:52

1

The orderByChild() sorting method is very forgiving. The children being sorted are not required to have a member with the specified field name. The documentation explains that those children are assigned a null value and appear first in the sort. Thus, if the reference used to create a query is incorrectly located, the query doesn't fail and instead will typically return all the children of that location.

You created your oldBug query using mDatabase where:

DatabaseReference mDatabase = FirebaseDatabase.getInstance().getReference();

This is one level too high. It should be:

 Query oldBug = mDatabase.child("Users").orderByChild("timeStamp").endAt(cutoff);

answered Dec 23 '16 at 23:52

Bob Snyder

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Thank you, this did it! By the way, I have a minor problem. How can I get it so that it deletes in real-time? – SaltySea Dec 24 '16 at 00:18
You'll have to explain what you mean by "in real-time". – Bob Snyder Dec 24 '16 at 00:28
For example, if I set the data to be deleted after 5 minutes, it should delete the data EXACTLY at 5 minutes. Not 5 minutes and until refresh. – SaltySea Dec 24 '16 at 00:33

score 0 · Answer 2 · answered Dec 23 '16 at 20:13

I think you might consider making a new child item that has a timestamp and date so that you can reference back to it when doing a query for the date and time. This way you don't have to worry about incorrect values and you can ensure you are deleting the correct data. I hope this helps.

Deleting Firebase data after a certain time

2 Answers2