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db.command.aggregate.toUpper

1. 操作符描述#

功能:将字符串转化为大写并返回。

声明:db.command.aggregate.toUpper(<表达式>)

2. 操作符参数#

字段类型必填说明
-Expression只要表达式可以被解析成字符串,那么它就是有效表达式。例如:$ + 指定字段

3. 示例代码#

假设集合 students 的记录如下:

{ "firstName": "Yuanxin", "group": "a", "lastName": "Dong", "score": 84 }{ "firstName": "Weijia", "group": "a", "lastName": "Wang", "score": 96 }{ "firstName": "Chengxi", "group": "b", "lastName": "Li", "score": 80 }

借助 toUpperlastName 的字段值转化为大写:

// 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()    .project({      _id: 0,      result: $.toUpper('$lastName')    })    .end()  console.log(res.data)}

返回的结果如下:

{ "result": "DONG" }{ "result": "WANG" }{ "result": "LI" }