MongoDB - How to aggregate data for each record

Question

I have some stored data like this:

{
    "_id" : 1,
    "serverAddresses" : {
        "name" : "0.0.0.0:8000",
        "name2": "0.0.0.0:8001"
    }
}

I need aggregated data to this:

[
  {
    "gameId": "1",
    "name": "name1",
    "url": "0.0.0.0:8000"
  },
  {
    "gameId": "1",
    "name": "name2",
    "url": "0.0.0.0:8001"
  }
]

What is the solution without using for loop?

Answer 1

1. $project - Add addresses field by converting $serverAddress to (key-value) array.
2. $unwind - Descontruct addresses field to multiple documents.
3. $replaceRoot - Decorate the output document based on (2).

db.collection.aggregate([
  {
    "$project": {
      "addresses": {
        "$objectToArray": "$serverAddresses"
      }
    }
  },
  {
    $unwind: "$addresses"
  },
  {
    "$replaceRoot": {
      "newRoot": {
        gameId: "$_id",
        name: "$addresses.k",
        address: "$addresses.v"
      }
    }
  }
])

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