CODEWITHSUNDEEP
arraysmongodbaggregation-framework
YulePale
YulePale

Reputation: 7736

MongoDB aggregation: Simple way to check if an array of numbers contains a negative number

Let say I have an array like so: [2,4,-6,-7,-3,5].

Is there a simple(not verbose) way of checking if an array contains a negative number in mongodb aggregation.

I will appreciate any answer. Even one that is verbose. I just prefer a less verbose one.

Upvotes: 0

Views: 835

Answers (1)

mitsos1os
mitsos1os

Reputation: 2290

If you want to just filter docs that have an array-property that contains a negative number, a simple { arrayField: { $lt: 0 } } would do.

Also if you just want to somehow categorize an array in aggregation, you could do the following.

For example, documents with schema:

{
  _id: 1,
  values: [2, -4, -6, -7]
}

you can add an extra boolean negative field on the documents and filter according to that later on in aggregation results:

db.collection.aggregate([
  {
    $addFields: {
      negative: {
        $reduce: {
          input: "$values",
          initialValue: false,
          in: {
            $or: ["$$value", { $lt: ["$$this",0] }]
          }
        }
      }
    }
  }
])

Upvotes: 1

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