node.js - 如何将 $split 运算符与聚合结合使用

Question

我想在日期字段上使用 $split 运算符。

[{
 "status": true,
 "beaconData" :{
    "date" : "15/07/2017, 11:00",
    "charge" : 15,
 },
 {
 "status": true,
 "beaconData" :{
    "date" : "2/07/2017, 15:00",
    "charge" : 35,
 },
 {
 "status": true,
 "beaconData" :{
    "date" : "2/07/2017, 11:05",
    "charge" : 5,
 }]

我就是这样用的

db.orders.aggregate( [ { $project:{data:{$split:["$beaconData.date", ", "] }, 'status':1 }}])

但错误返回如下

"errmsg" : "exception: invalid operator '$split'",

"code" : 15999,

Answer 1

//$split works in 3.4 u can use $substr in ur case if ur date is always in the same format you asked
 db.orders.aggregate(
       [
         {
           $project:
              {
                data: { $substr: [ "$beaconData.date", 0, 9 ] }
              }
          }
       ]
    )