How in Monge to write the value of an object's property to another property of the same object?

Question

MongoDB

Strange title, I'll explain now. I have an object -

{
  name: 'qwerty',
  nameToo: '12345'
}

How do I write the value from nameToo to name ?
I tried with this, but it, logically, points to the wrong thing:

db.getCollection('collection').update({nameToo: {$exists:1}},{$set: {name: this.nameToo}}, {multi:true})

name: undefined

Answer 1

I don’t hear an answer, I also had to look for Pts for a long time in Google, I’ll write here, all of a sudden someone needs it)

db.getCollection('collection').find({
                nameToo: {$exists:1}
                }).forEach(
    function (elem) {
        db.getCollection('collection').update(
            {
                _id: elem._id
            },
            {
                $set: {
                    name: elem.nameToo
                }
            }
        );
    }
);

I say right away that if you have 10,000+ such objects in the database, the script will not run quickly.
It gave me an incomprehensible error, but it worked on almost all objects. I had to replace all the necessary objects with a random
one through the usual one , and then in the script above, make a selection in this already . Then everything is fine. updatenamefindname

Answer 2

$lookup + $out in aggregation pipe line is the
first thing that comes to mind if you want to do it in 1 query.
In general, combinations of operators depend on the difference between documents and the result you want to achieve. But the variations are practically unlimited.