how to replace the root with object value in MongoDB

Question

Document 1:

{
  "data": {
    "id": "123456",
    "name": "abc",
    "value": 1
  }
}

Expected Output-

{
  "abc": {
    "id": "123456",
    "name": "abc",
    "value": 1
  }
}

Explanation: How we can replace the root with the " name" value, check the expected output, whatever value of the "name", it becomes on the root level. and I have multiple documents. Thanks in advance.

Raymond Reddington · Accepted Answer · 2021-02-17 07:01:21Z

2

You can achieve this via $project aggregation. It should be something like this:

{ $project: { "$data.name": "$data" } }

answered Feb 17, 2021 at 7:01

Raymond Reddington

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Tom Slabbaert · Accepted Answer · 2021-02-17 07:17:35Z

0

Mongo doesn't allow field names to start with a $ meaning you can't define a dynamic key name.

You'll have to work around this restriction by playing with the data structure, here is an example of how to achieve this with $arrayToObject

db.collection.aggregate([
  {
    "$replaceRoot": {
      "newRoot": {
        "$arrayToObject": [
          [
            {
              k: "$data.name",
              v: "$data"
            }
          ]
        ]
      }
    }
  }
])

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answered Feb 17, 2021 at 7:17

Tom Slabbaert

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