Question 349065 in Mongodb Question posted in
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Mongodb – How to use $unset when the key being removed contains a dot in its name?

How to use $unset when a key contains dots in its name?

const key = "test"
const result = await db.collection(collection).updateOne(
    { [key]: { $exists: true } },
    { $unset: { [pathToKey]: 1 } }
);

given this document:

{
  "test": {
    "a": "b",         // <- test.a successfully erases the 'a' key
    "v0.0.1": "ok"    // <- test.v0.0.1 fails
  }
}

when pathToKey is 'test.a' it successfully erases the a key

when it 'test.v0.0.1' it fails, probably because the key contains a . in its name

I’m using the latest Mongo version

https://mongoplayground.net/p/Chiy7DtIqWb

I also tried using $unsetField: https://mongoplayground.net/p/MNyfhh1vdDW

Tags:

2

Answers


  1. 0

    The keys with dots are not supported by MongoDB
    http://docs.mongodb.org/manual/reference/limits/#Restrictions-on-Field-Names

    Maybe you could use a workaround but i think it will be better to use different keys

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  2. 0

    You can use $setField with $$REMOVE

    db.collection.aggregate([
  {
    "$match": {
      $expr: {
        $ne: [
          {
            "$ifNull": [
              "$test",
              {}
            ]
          },
          {}
        ]
      }
    }
  },
  {
    "$set": {
      "test": {
        "$setField": {
          "field": "v0.0.1",
          "input": "$test",
          "value": "$$REMOVE"
        }
      }
    }
  },
  {
    "$merge": {
      "into": "collection",
      "on": "_id"
    }
  }
])

    Mongo Playground

    For a nested object, chain up the above solution with $mergeObjects

    db.collection.aggregate([
  {
    "$set": {
      "test": {
        "$mergeObjects": [
          "$test",
          {
            "b": {
              "$setField": {
                "field": "b",
                "input": "$test.b",
                "value": "$$REMOVE"
              }
            }
          }
        ]
      }
    }
  }
])

    Mongo Playground

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