Question 115285 in Mongodb Question posted in
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Mongodb – Add counter field to all documents using mongo shell

I need to add a missing counter field in my documents using the mongoshell (v4).

In JS I would do something like this:

const affected = await Data.findMany({ dataId: { $exists: false }}).toArray()
affected.map((d, i) => {
    Data.updateOne({ _id: d._id }, { $set: { dataId: i + 1 }})
})

Is it possible to do this directly in the shell?

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2

Answers


  1. 0

    It’s almost identical.

    Mongo shell provides the capability to use JavaScript code directly in the shell.

    use your_database

const affected = db.data.find({ dataId: { $exists: false }}).toArray()
affected.map((d, i) => { db.data.updateOne({ _id: d._id }, { $set: { dataId: i + 1 }}) })
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  2. 0

    This can also be done using a single query:

    db.collection.aggregate([
  {$match: {dataId: {$exists: false}}},
  {$setWindowFields: {
      sortBy: {_id: 1},
      output: {dataId: {
          $sum: 1,
          window: {documents: ["unbounded", "current"]}
      }}
  }},
  {$merge: {into: "collection"}}
])

    See how it works on the playground example

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