db.command.aggregate.size

1. Operator Description

Function: Returns the length of the array.

Declaration: db.command.aggregate.size(array)

2. Operator Parameters

Field	Type	Required	Description
-	Expression	Required	Can be any expression that resolves to an array.

3. Sample Code

Suppose the collection shops contains the following records:

{ "_id": 1, "staff": [ "John", "Middleton", "George" ] }
{ "_id": 2, "staff": [ "Steph", "Jack" ] }

Count the number of employees in each store:

// 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('staff')
    .aggregate()
    .project({
      totalStaff: $.size('$staff')
    })
    .end()
  console.log(res.data)
}

The returned result is as follows:

{ "_id": 1, "totalStaff": 3 }
{ "_id": 2, "totalStaff": 2 }