Clould Firestore - queries with fields of type dates

Question

I'm having difficulty performing queries with date type (timestamp). How would the correct way of querying date fields in the cCoud Firestore be?

    String created_view = editTextDataFilter.getText().toString();
    String time_variable= "";

    try {

        time_variable= new SimpleDateFormat("EEE MMM dd HH:mm:ss z yyyy", Locale.ENGLISH).format(new SimpleDateFormat(
                "dd/mm/yyyy", Locale.ENGLISH).parse(created_view));

    }catch (ParseException e){}


db.collection("Students")
            .whereGreaterThan("created_at", time_variable)
            .get()
            .addOnCompleteListener(new OnCompleteListener<QuerySnapshot>() {
                @Override
                public void onComplete(@NonNull Task<QuerySnapshot> task) {
                    if (task.isSuccessful()) {

                        for (QueryDocumentSnapshot document : task.getResult()) {

                            alunosList.add(
                                    new Students(
                                            document.getString("name").toUpperCase(),
                                            document.getString("classroom"),
                                            document.getDate("created_at")));


                            recyclerView.setAdapter(adapter);
                        }
                    }
                    else {
                        Log.w(TAG, "Error getting documents.", task.getException());
                    }
                }
            });


}

Field Timestamp

I expect the output to bring the records with a date greater than the value entered in the "time_variable", but currently it does not find values.

Pass a Date or Timestamp object, not a string. – Doug Stevenson Apr 02 '19 at 02:58 — Doug Stevenson, Apr 02 '19 at 02:58

score 0 · Accepted Answer · answered Apr 02 '19 at 06:23

In order to be able to query a Firestore database based on a timestamp, you need to pass to the CollectionReference's whereGreaterThan(FieldPath fieldPath, Object value) method a Date object. Passing a String (as you currently do), it won't make your query work.

A query that it will work, should look like this:

SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
Date date = dateFormat.parse(created_view);
db.collection("Students")
        .whereGreaterThan("created_at", date)
        .get()
        .addOnCompleteListener(/* ... */);

If you want to add a timestamp programmatically, plese see my answer from the following code:

ServerTimestamp is allways null on Firebase Firestore

Sorry for the delay in answering. It worked, thank you. I change only SimpleDateFormat dateFormat = new SimpleDateFormat("dd/MM/yyyy"); — josé nunes, Apr 03 '19 at 12:24

Clould Firestore - queries with fields of type dates

1 Answers1