Question 118639 in Mongodb Question posted in
The official documentation can be found here.

How to use sort() in MongoDB update statements?

I just want to update the top 2 highest fields in the database.

db.Employee.update({
    db.Employee.find().sort({
      Age: -1
    }).limit(2) --This part here wont work--
  },

  {
    $set: {
      Benefits: ["Vacation", "Rolex"]
    }
  }
)

Apparently MongoDB does not support such ability.
How can I dynamically update the top 2 highest fields of my DB?

I do not want to resort to find the _id of the collection manually and then update the collection separately.

Tags:

2

Answers


  1. 0

    Something simple like this can do the job:

    db.Employee.find({}).sort({Age:-1}).limit(2).forEach(function(doc){
db.Employee.update({_id:doc._id},{$set:{Benefits:["Vacation","Rolex"]}})
})
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  2. 0

    Starting in MongoDB 4.4, there is a $merge stage in the aggregation that can allow updating the same collection with the aggregation results, so you can do something like this:

        db.Employee.aggregate([
  {
    $sort: {
      Age: -1
    }
  },
  {
    $limit: 2
  },
  {
    $set: {
      Benefits: [
        "Vacation",
        "Rolex"
      ]
    }
  },
  {
    $merge: {
      into: "Employee",
      on: "_id",
      whenMatched: "replace",
    }
  }
])

    I tried it on my own db and it works, even though I could not make the playground update its own collection.
    The documentation for the $merge can be found here

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