Hi,

In mongo shell, the following aggregation pipeline works as expected: it finds all documents of which the string length of the value of the "un" field is 25.

db.configusers.aggregate([{
    "$match": {
        "$expr": {
            "$eq": [
                {'$strLenCP': "$un"}, 25 ]
        }
    }
}

However, I use this in Compass 1.18, it will report Field must not begin with '$' or '.', field path was: $strLenCP:

Similarly, other operators such as $abs, $trim are not supported as well.

Could you please confirm if this is expected and if there is a plan to support operators in such use cases?

Regards,
Lungang