db.command.aggregate.multiply
1. 操作符描述
功能:取传入的数字参数相乘的结果。
声明:db.command.aggregate.multiply([expression1, expression2, ...])
2. 操作符参数
字段 | 类型 | 必填 | 说明 |
---|---|---|---|
- | Expression | 是 | 参数可以是任意解析为数字的表达式。 |
3. 示例代码
假设集合 fruits
有如下记录:
{ "_id": 1, "name": "apple", "price": 10, "quantity": 100 }
{ "_id": 2, "name": "orange", "price": 15, "quantity": 50 }
{ "_id": 3, "name": "lemon", "price": 5, "quantity": 20 }
求各个水果的的总价值:
// 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.aggregate
const _ = db.command
exports.main = async (event, context) => {
const res = await db
.collection('fruits')
.aggregate()
.project({
name: 1,
total: $.multiply(['$price', '$quantity'])
})
.end()
console.log(res.data)
}
返回结果如下:
{ "_id": 1, "name": "apple", "total": 1000 }
{ "_id": 2, "name": "orange", "total": 750 }
{ "_id": 3, "name": "lemo", "total": 100 }