Weired Problem with Date field query returning zero results only using Atlas Data API

I created a free M0 mongodb cluster in the Atlas Cloud.

I added about 400.000 documents with book data using python MongoClient.
The documents contain a field “publicationDate” of the type “Date” which i defined as follows in python:

pubDateFormatted = pubDate.strftime("%Y-%m-%dT00:00:00Z")
document {
"publicationDate": { "$date": pubDateFormatted }

Now I am able to query all books from the year 2022 by defining the filter as follows in python and get the correct results:

filter = {
    "type": "pbook",
    "publicationDate": {
        "$gte": {
            "$date": "2022-01-01T00:00:00Z"
        "$lte": {
            "$date": "2022-12-31T23:59:59Z"

Now the problem:
I created a small HTML page to display all books. That uses a little php script and the Atlas DATA API to query the data. The API queries work, but as soon as i add the filter for the year it returns zero results.

$filter = array('type' => 'pbook');
if (!empty ($year))
    $filter['pubDate2'] =
            '$gte' => array(
                '$date' => "2022-01-01T00:00:00Z"
            '$lte' => array(
                '$date' => "2022-12-31T23:59:59Z"

I also get no results when I run the query in the Atlas admin backend, although the field “publicationDate” is clearly marked with the type “Date” there!

What am I doing wrong?

I think that

should be
$filter['publicationDate'] =

Oh, sorry, i have been testing a lot and copied the wrong code.
I get zero results also when using $filter[‘publicationDate’] = …

When i query all documents where publicationDate is of type “Date”, i get zero results.
filter = {"publicationDate": {"$type": "date"}}

Even in python, where filtering by date is working, i get zero results for this:

filter = {"publicationDate": {"$type": "date"}}
> 0

im really confused.

How many documents if you use an empty filter jn

I get 380191 results with empty filter

can you print out some of the results, a screenshot of the same document in compass would also be nice

Thanks for pointing me to Compass. I’m still very new to mongodb.

In Atlast Cloud Backend it says “Date”, in Compass it says “Object”. (Is Date an object? Or did i save it the wrong way?)


And thats the document:

  "_id": {
    "$oid": "64e73f03ed4d31d42c8d7b58"
  "title": "Wie die Stille vor dem Fall. Zweites Buch: Special Edition",
  "isbn": "9783736321670",
  "publicationDate": {
    "$date": "2023-07-28T00:00:00Z"
  "type": "pbook",

Are you sure you are looking at the same document?

I am not.

The one in Atlas has an appropriate date that ends with .0000+00:00 while the other one ends with Z.

It looks like the document 64e73f03ed4d31d42c8d7b58 really has a field named publicationDate which is an object that has a field named $date with a string value.

That would explain that you get:

Try the queries

filter = {"publicationDate.$date": {"$type": "string"}}


filter = {"publicationDate.$date" : "2023-07-28T00:00:00Z" }