Issues with MongoDB Querying Nested Documents Using spring-boot-starter-data-mongodb

I’m encountering some issues when querying nested MongoDB documents using spring-boot-starter-data-mongodb.

After checking, I can confirm that the valid documents are present in MongoDB. Here's an example:

[
  {
    "_id": {"$oid": "67e0261f4b8ed21de1e2afb5"},
    "_class": "com.ucapital.adv.documents.BannerDoc",
    "balance": 52.94,
    "costs": {
      "costPerClick": 1.31,
      "costPerImpression": 62.48
    },
    "createdAt": {"$date": "2025-03-23T15:17:51.078Z"},
    "description": "Neque distinctio velit vel sed sed molestias accusamus.",
    "enabled": true,
    "imageUrl": "http://lorempixel.com/1024/768/city/image.jpg",
    "link": "www.lesa-heaney.org",
    "metrics": {
      "clicks": 6,
      "impressions": 173
    },
    "priority": 3,
    "title": "aspernatur accusamus et",
    "updatedAt": {"$date": "2025-03-23T15:17:51.078Z"},
    "validFrom": {"$date": "2025-02-02T15:17:51.023Z"},
    "validTo": {"$date": "2025-06-11T15:17:51.023Z"}
  }
]

First approach with Criteria:

public static Criteria isNotExpired() {
    Date currentDate = new Date();
    return where("validFrom").lte(currentDate)
            .andOperator(where("validTo").gte(currentDate));
}

public static Criteria isEnabled() {
    return where("enabled").is(true);
}

public static Criteria hasBudget() {
    return new Criteria().orOperator(
            where("balance").gte("$costs.costPerClick"),
            where("balance").gte("$costs.costPerImpression")
    );
}

List<Criteria> criteriaList = List.of(isEnabled(), isNotExpired(), hasBudget());
Query query = Query.query(new Criteria().andOperator(criteriaList.toArray(new Criteria[criteriaList.size()])));
System.out.println(query.getQueryObject());  // Log the query
long total = mongoTemplate.count(query, BannerDoc.class);

The number of documents retrieved is 0. The issue is with the hasBudget Criteria because when I remove it, the objects are retrieved correctly.

Fallback approach using aggregations:

Aggregation aggregation = Aggregation.newAggregation(
        Aggregation.match(Criteria.where("enabled").is(true)),

        Aggregation.project()
                .andExpression("balance >= costs.costPerClick && balance >= costs.costPerImpression")
                .as("hasBudget"),

        Aggregation.match(Criteria.where("hasBudget").is(true))
);

List<BannerDoc> banners = mongoTemplate.aggregate(aggregation, "banners", BannerDoc.class).getMappedResults();
System.out.println(banners);

In this case, the elements are retrieved, but all the attributes of the object are null.

Does anyone know what’s wrong with my hasBudget Criteria, or can anyone help me resolve the aggregation fallback approach?

Thanks!

If anyone is interested, I resolved the issue this way:

public static Criteria hasBudget() {
    MongoExpression expr1 = ComparisonOperators.Gte
            .valueOf("$balance")
            .greaterThanEqualToValue(ConvertOperators.ToDouble.toDouble("$costs.costPerClick"));
    MongoExpression expr2 = ComparisonOperators.Gte
            .valueOf("$balance")
            .greaterThanEqualToValue(ConvertOperators.ToDouble.toDouble("$costs.costPerImpression"));
    
    return Criteria.where("$or").is(List.of(
            Criteria.expr(expr1),
            Criteria.expr(expr2)
    ));
}