db.command.aggregate.sqrt

1. Operator Description

Function: Compute the square root.

Syntax: db.command.aggregate.sqrt([number])

2. Operator Parameters

Field	Type	Required	Description
-	<Array>Expression	Required	The parameter can be any expression that resolves to a non-negative number.

3. Sample Code

Suppose the right triangle collection triangle contains the following records:

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

Suppose x and y are the two legs of a right triangle, then calculate the length of the hypotenuse:

// 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('triangle')
    .aggregate()
    .project({
      len: $.sqrt([$.add([$.pow(['$x', 2]), $.pow(['$y', 2])])])
    })
    .end()
  console.log(res.data)
}

The returned result is as follows:

{ "_id": 1, "len": 3.605551275463989 }
{ "_id": 2, "len": 8.602325267042627 }
{ "_id": 3, "len": 22.360679774997898 }