db.command.aggregate.concatArrays
#
1. 操作符描述功能:将多个数组拼接成一个数组。
声明:db.command.aggregate.arrayToObject([ array1, array2, ... ])
#
2. 操作符参数字段 | 类型 | 必填 | 说明 |
---|---|---|---|
- | <Array>Expression | 是 | 表达式可以是任意解析为数组的表达式。 |
#
3. 示例代码假设集合 items
有如下记录:
{ "_id": 1, "fruits": [ "apple" ], "vegetables": [ "carrot" ] }{ "_id": 2, "fruits": [ "orange", "lemon" ], "vegetables": [ "cabbage" ] }{ "_id": 3, "fruits": [ "strawberry" ], "vegetables": [ "spinach" ] }
// 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
exports.main = async (event, context) => { const res = await db .collection('items') .aggregate() .project({ sales: $.concatArrays(['$fruits', '$vegetables']) }) .end() console.log(res.data)}
返回结果如下:
{ "_id": 1, "first": 80, "last": 90 }{ "_id": 2, "first": 78, "last": 78 }{ "_id": 3, "first": 95, "last": 92 }