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I want to set a field to a value of a nested field

given

{
  "_id":"myId",
  "data":{
    "id":"asdfasdfasdf",
    "text":"Wonderful text"
  }
}

expected

{
  "_id":"myId",
  "messageId":"asdfasdfasdf",
  "data":{
    "id":"asdfasdfasdf",
    "text":"Wonderful text"
  }
}

Is there a possibility to do something like this?

db.myCollection.updateMany({},{ $set: {"messageId": "$data.id"} },false,true)

I am using MongoCompass -> _MongoSH

over 4 years ago · Santiago Trujillo

Answer question

Accepted Answer · 2022-05-12T20:25:40.704Z

Yes, it's possible doing this using pipelined updates, added at version 4.2.

This is how you use it:

db.collection.updateMany(
{},
[
  {
    $set: {
      "message": "$data.id"
    }
  }
])

For lesser Mongo versions you have to read the document first and then use the values for the update.