MongoDB update arrays entry

Question

I have a document to Mongodb update array of objects like this:

    {
    "myArray": [
            {
              "Key1": "string",
              "key2": {
                "entry": "aaa"
              }
            },
            {
              "Key1": "string",
              "key2": {
                "entry": "bbb"
              }
            }
          ]
    }

And I want to modify the key2 field in each object of myArray. The expected result should be :

    {
    "myArray": [
            {
              "Key1": "string",
              "key2Modified":"aaa"
            },
            {
              "Key1": "string",
              "key2Modified":"bbb"
            }
          ]
    }

Any help please ?

Answer 1

use $map in $set

db.collection.update({},
[
  {
    $set: {
      "myArray": {
        $map: {
          input: "$myArray",
          as: "a",
          in: {
            Key1: "$$a.Key1",
            key2Modified: "$$a.key2.entry"
          }
        }
      }
    }
  }
])

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