AggregateCommand.multiply(value: Expression[]): Object
聚合操作符。取传入的数字参数相乘的结果。
参数
value: Expression[]
[<expression1>, <expression2>, …]
返回值
Object
API 说明
语法如下:
db.command.aggregate.multiply([<expression1>, <expression2>, ...])
参数可以是任意解析为数字的表达式。
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:
const $ = db.command.aggregate
db.collection('fruits').aggregate()
.project({
name: 1,
total: $.multiply(['$price', '$quantity']),
})
.end()
返回结果如下:
{ "_id": 1, "name": "apple", "total": 1000 }
{ "_id": 2, "name": "orange", "total": 750 }
{ "_id": 3, "name": "lemo", "total": 100 }