db.command.aggregate.multiply
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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, ...])
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2. 操作符参数字段 | 类型 | 必填 | 说明 |
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- | Expression | 是 | 参数可以是任意解析为数字的表达式。 |
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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.aggregateconst _ = 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 }