db.command.aggregate.range

1. Operator Description

Description: Returns a sequence of generated numbers. Given a start value, end value, and a non-zero step, range returns a sequence starting from the start value, incrementing by the specified step, and excluding the end value.

Declaration: db.command.aggregate.range([<start>, <end>, <non-zero step>])

2. Operator Parameters

Field	Type	Required	Description
-	<Array>Expression	Required	array of aggregate expressions

Field	Type	Required	Description
start	Expression	Required	Start value, an expression that can be resolved to an integer
end	Expression	Required	End value, an expression that can be resolved to an integer
non-zero step	number	No	Optional. Step size, an expression that can be resolved to a non-zero integer. Default is 1.

3. Sample Code

Suppose the collection stats contains the following records:

{ "_id": 1, "max": 52 }
{ "_id": 2, "max": 38 }

// Sample code in the Cloud Function environment
const tcb = require('@cloudbase/node-sdk')
const app = tcb.init({
  env: 'xxx'
})

const db = app.database()
const $ = db.command.aggregate
const _ = db.command

exports.main = async (event, context) => {
  const res = await db
    .collection('stats')
    .aggregate()
    .project({
      points: $.range([0, '$max', 10])
    })
    .end()
  console.log(res.data)
}

The returned result is as follows:

{ "_id": 1, "points": [0, 10, 20, 30, 40, 50] }
{ "_id": 2, "points": [0, 10, 20] }