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db.command.aggregate.push

1. 操作符描述#

功能:在 group 阶段,返回一组中表达式指定列与对应的值,一起组成的数组。

声明:db.command.aggregate.push({ <字段名1>: <指定字段1>, <字段名2>: <指定字段2>, ... })

2. 操作符参数#

字段类型必填说明
-Object对象键值为任意聚合表达式

3. 示例代码#

假设集合 students 的记录如下:

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

借助 push 操作,对不同分组( group )的所有记录,聚合所有数据并且将其放入一个新的字段中,进一步结构化和语义化数据。

// 云函数环境下示例代码const tcb = require('@cloudbase/node-sdk')const app = tcb.init({  env: 'xxx'})
const db = app.database()const $ = db.command.aggregateconst _ = 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)}

输出结果如下:

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