$range (array expression)

APPLIES TO: MongoDB vCore

The $range operator is used to generate an array of sequential integers. This operator is particularly useful for creating arrays of numbers within a specific range, which can then be used for various purposes such as pagination, indexing, or generating test data.

The syntax for the $range operator is:

$range: [ <start>, <end>, <step> ]

Here are some examples demonstrating the use of the $range operator.

To generate an array of integers from 0 to 9:

db.stores.aggregate([
  { $match: { "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60"} }
, {
    $project: {
      rangeArray: { $range: [0, 5] }
    }
  }
])

The query results in generating an array of sequential numbers.

{
    "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60",
    "rangeArray": [ 0, 1, 2, 3, 4 ]
}

To generate an array of even numbers from 0 to 18:

db.stores.aggregate([
  { $match: { "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60"} }
, {
    $project: {
      evenNumbers: { $range: [0, 8, 2] }
    }
  }
])

The query results in generating an array of even numbers, stepping by 2.

{
    "_id": "988d2dd1-2faa-4072-b420-b91b95cbfd60",
    "rangeArray": [ 0, 2, 4, 6 ]
}

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