# AggregateCommand.objectToArray(value: Expression<object>): Object
聚合操作符。将一个对象转换为数组。方法把对象的每个键值对都变成输出数组的一个元素,元素形如 { k: <key>, v: <value> }
。
# 参数
# value: Expression<object>
# 返回值
# Object
# API 说明
语法如下:
db.command.aggregate.objectToArray(<object>)
# 示例代码
假设集合 items
有如下记录:
{ "_id": 1, "attributes": { "color": "red", "price": 150 } }
{ "_id": 2, "attributes": { "color": "blue", "price": 50 } }
{ "_id": 3, "attributes": { "color": "yellow", "price": 10 } }
const $ = db.command.aggregate
db.collection('items').aggregate()
.project({
array: $.objectToArray('$attributes')
})
.end()
返回结果如下:
{ "_id": 1, "array": [{ "k": "color", "v": "red" }, { "k": "price", "v": 150 }] }
{ "_id": 2, "array": [{ "k": "color", "v": "blue" }, { "k": "price", "v": 50 }] }
{ "_id": 3, "array": [{ "k": "color", "v": "yellow" }, { "k": "price", "v": 10 }] }