How to get the value of a field when selecting?

Question

MongoDB

Whether prompt it is possible as that to learn value of a field in the document at sampling in the condition.
I have some numeric settings in my config

config.basic.i = 10; //10 минут
config.average.i = 20; // 20 минут

The document has a field field equal to either basic or average, as well as a field with the date of the last update updateAt
I need to get a document in which the field

updateAt < new Date(new Date().setMinutes(new Date().getMinutes()-config['$field'].i))

Something like this

Coll.findOne({
    updateAt: {
        $lte: new Date(new Date().setMinutes(new Date().getMinutes()-config['$field'].i))
    }
})

Without approximately such a condition, you will have to receive all documents, compare the field in a cycle, I would not want to do this if you can, of course, avoid this. Maybe with .aggregate it's possible like that?

Answer 1

Keep a calculated field in the document (updateed - minutes from the document), and use it already