Sort after retrieving data from Firestore but before populating recyclerview

Question

Problem:

I am storing events (think calendar events) in Firestore and the times as Strings because timestamps in Firestore seem to be something else. Ex. 10:00 AM, 10:00 PM, etc. I want to display these events in my RecyclerView sorted by time.

Is it possible to sort them before populating the RecyclerView? I tried looking and found nothing online and don't know how to approach this problem.

I am using FirebaseUI and I'm guessing this has to happen in the Adapter somewhere

Query query = firebaseFirestore.collection(year).whereIn("location", "Park").orderBy("time", Query.Direction.ASCENDING);
                    //Recycler options
                    FirestoreRecyclerOptions < EventModel > options = new FirestoreRecyclerOptions.Builder < EventModel > ()
                            .setQuery(query, EventModel.class)
                            .build();

                    eventAdapter = new EventAdapter(options);
                    mFirestoreList.setAdapter(eventAdapter);
                    eventAdapter.startListening();
                    eventAdapter.notifyDataSetChanged();

You can use `Date` data type to store dates. `FirebaseFirestore` supports query and operations on `Date` field. — Hussain, Jul 13 '20 at 07:05

score 1 · Answer 1 · answered Jul 13 '20 at 07:29

If you want to get accurate results when querying a Firestore database, you should use either a java Date or a Firestore Timestamp object, but definitely not a String. I'm saying that, because the way String objects are ordered, is lexicographic and the result that you'll get will not be much of a help.

To be able to add a Timestamp value, you can use the solution from my following answer:

ServerTimestamp is always null on Firebase Firestore

The query that you are actually using should not be changed, it will work the way it is right now.

Sort after retrieving data from Firestore but before populating recyclerview

1 Answers1