Convert (update) number to array mongoDB

Question

I have the following documents

{ _id:"myId", balance:1 }

and I want to change the field in number type to an array with the same number.

{ _id:"myId", balance: [1], }

tried

Collection.updateMany({ balance: { $type: 'number' } }, { $set: { balance: ["$balance"] } });

, didn't work ($balance string). How can i do this?

@NeNaD solution below seems best for latest versions 4.2+ , here there is some ideas on how to do in different other mongo versions: stackoverflow.com/questions/3974985/… — R2D2
– R2D2, Commented Oct 24, 2022 at 8:01

NeNaD · Accepted Answer · 2022-10-24 07:56:18Z

1

You have to wrap the update config with [] since you are using aggregation framework to update:

db.collection.update({
  balance: {
    $type: "number"
  }
},
[
  {
    $set: {
      balance: [
        "$balance"
      ]
    }
  }
])

answered Oct 24, 2022 at 7:56

NeNaD

20.8k11 gold badges64 silver badges118 bronze badges

Sign up to request clarification or add additional context in comments.

1 Answer 1