db.command.aggregate.push

1. Operator Description

Function: In the group stage, returns an array composed of the expression-specified column and its corresponding values within a group.

Declaration: db.command.aggregate.push({ <fieldName1>: <specifiedField1>, <fieldName2>: <specifiedField2>, ... })

2. Operator Parameters

Field	Type	Required	Description
-	Object	Yes	The object key-value is any aggregation expression.

3. Sample Code

Suppose the collection students contains the following records:

{ "group": "a", "name": "stu1", "score": 84 }
{ "group": "a", "name": "stu2", "score": 96 }
{ "group": "b", "name": "stu3", "score": 80 }
{ "group": "b", "name": "stu4", "score": 100 }

Using the push operator, for all records in different groups (group), it aggregates all data and places it into a new field, further structuring and adding semantic meaning to the data.

// 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('students')
    .aggregate()
    .group({
      _id: '$group',
      students: $.push({
        name: '$name',
        score: '$score'
      })
    })
    .end()
  console.log(res.data)
}

The output is as follows:

{ "_id": "b", "students": [{ "name": "stu3", "score": 80 }, { "name": "stu4", "score": 100 }] }
{ "_id": "a", "students": [{ "name": "stu1", "score": 84 }, { "name": "stu2", "score": 96 }] }