Question 115223 in Mongodb Question posted in
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Wrap all fields of MongoDB Document into a root/top level object

Suppose I have two documents in a collection:

[
  {
    "_id": 0,
    "name": "aaaa",
    "phone": 111
  },
  {
    "_id": 1,
    "name": "bbbb",
    "phone": 999
  }
]

I want to run an aggregation pipeline that will merge/wrap/combine ALL the fields into a top-level root object called lead. Without mentioning/hardcoding the field names in the query.

Expected output:

[
  {
    "lead": {
      "_id": 0,
      "name": "aaaa",
      "phone": 111
    }
  },
  {
    "lead": {
      "_id": 1,
      "name": "bbbb",
      "phone": 999
    }
  }
]
Tags:

2

Answers


  1. Chosen as BEST ANSWER
    0

    Got some help from this answer and was able to achieve it using $project:

    db.collection.aggregate([
  {
    $project: {
      lead: "$$ROOT",
      _id: false
    }
  }
])

    Playground link

    $$ROOT in MongoDB references the content of this document.


  2. 0

    Works with $replaceWith stage to replace the input documents with new outputdocuments. To get each (original) document, you need to use the $$ROOT variable.

    db.collection.aggregate([
  {
    $replaceWith: {
      "lead": "$$ROOT"
    }
  }
])

    Demo @ Mongo Playground

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