How to join two arrays into fields of object

Question

In mongodb aggregate, I have below document:

{key:['a','b','c'], scores:[1,2,3]}

And want to change it to

{a:1, b:2, c:3}

How to do it in aggregate stage? I'm using MongoDB Compass Version 1.21.2 (1.21.2)

Answer 1

You can use $zip

play

db.collection.aggregate([
  {
    $project: {
      "output": {
        "$zip": {
          "inputs": [
            "$key",
            "$scores"
          ],
          
        }
      }
    }
  }
])

It maps the values the way you need but the format is different.

You can use $unwind, $project, $arrayToObject to convert further to the object structure.

As @turivishal pointed out, you can convert the above to the desired structure using (this)[mongoplayground.net/p/PSnIzI8nF0A].