Spring Data: MongoDB criteria using $toDouble

Question

I have this console query:

db.testcol.find({ $expr: { $lte: [ { $toDouble: "$someField" }, 5 ] } })

I want to write it programmatically using Criteria so I can do the following:

mongoTemplate.find(new Query(criteria), MyClass.class)

I tried:

Criteria criteria = Criteria.where("someField").lte(5)

But I don't really know where I can put the $toDouble part.

Thanks in advance!

Answer 1

You need to call Criteria.expr() method:

MongoExpression expr = ComparisonOperators.Lte
              .valueOf(ConvertOperators.ToDouble.toDouble("$someField"))
              .lessThanEqualToValue(5);     
Criteria criteria = Criteria.expr(expr);
mongoTemplate.find(Query.query(criteria), MyClass.class);

Alternative solution: Not all MongoDB queries are easily done in the "Spring way". You may run the query operator JSON this way:

collection.find(query) == collection.aggregate([{"$match": query}])

---

Aggregation agg = Aggregation.newAggregation(ctx -> new Document("$match", 
    Document.parse("{ $expr: { $lte: [ { $toDouble: '$someField' }, 5 ] } }")));        
mongoTemplate.aggregate(agg, MyClass.class, MyClass.class).getMappedResults();