db.command.aggregate.concatArrays

1. Operator Description

Function: Concatenates multiple arrays into a single array.

Declaration: db.command.aggregate.arrayToObject([ array1, array2, ... ])

2. Operator Parameters

Field	Type	Required	Description
-	<Array>Expression	Required	The expression can be any expression that resolves to an array.

3. Sample Code

Suppose the collection items contains the following records:

{ "_id": 1, "fruits": [ "apple" ], "vegetables": [ "carrot" ] }
{ "_id": 2, "fruits": [ "orange", "lemon" ], "vegetables": [ "cabbage" ] }
{ "_id": 3, "fruits": [ "strawberry" ], "vegetables": [ "spinach" ] }

// 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

exports.main = async (event, context) => {
  const res = await db
    .collection('items')
    .aggregate()
    .project({
      sales: $.concatArrays(['$fruits', '$vegetables'])
    })
    .end()
  console.log(res.data)
}

The returned result is as follows:

{ "_id": 1, "first": 80, "last": 90 }
{ "_id": 2, "first": 78, "last": 78 }
{ "_id": 3, "first": 95, "last": 92 }