db.command.aggregate.pow

1. Operator Description

Function: Computes the power of a given base raised to an exponent.

Declaration: db.command.aggregate.pow([base, exponent])

2. Operator Parameters

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

3. Sample Code

Suppose the collection stats contains the following records:

{ "_id": 1, "x": 2, "y": 3 }
{ "_id": 2, "x": 5, "y": 7 }
{ "_id": 3, "x": 10, "y": 20 }

Calculate the sum of squares of x and y:

// 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({
      sumOfSquares: $.add([$.pow(['$x', 2]), $.pow(['$y', 2])])
    })
    .end()
  console.log(res.data)
}

The returned result is as follows:

{ "_id": 1, "sumOfSquares": 13 }
{ "_id": 2, "sumOfSquares": 74 }
{ "_id": 3, "sumOfSquares": 500 }