来自多个对象的MongoDb $avg

Question

我从下面的代码中获得了数据：

db.getCollection('lampus').aggregate([
  {
      $unwind: '$data'
  },
{
$match: {_id: "sensor-2",
  'data.tanggal': {
    $gt: (new Date(new ISODate()-1*1000*60*60*24))
  }
}
}, 
{
$sort: {
  'data.tanggal': 1
}
},

])

结果是：

[{"_id":"sensor-2","data":{"sensor": 
{"intensitas":3,"arus":0.05},"tanggal":"2018-08-05T14:05:58.757Z"}},
{"_id":"sensor-2","data":{"sensor": 
{"intensitas":11,"arus":0.05},"tanggal":"2018-08-05T14:05:58.756Z"}},
{"_id":"sensor-2","data":{"sensor": 
{"intensitas":8,"arus":0.05},"tanggal":"2018-08-05T14:05:52.654Z"}},
{"_id":"sensor-2","data":{"sensor": 
{"intensitas":13,"arus":0.05},"tanggal":"2018-08-05T14:05:51.152Z"}},
{"_id":"sensor-2","data":{"sensor": 
{"intensitas":15,"arus":0.05},"tanggal":"2018-08-05T14:05:46.651Z"}},
{"_id":"sensor-2","data":{"sensor": 
{"intensitas":13,"arus":0.1},"tanggal":"2018-08-04T14:05:45.150Z"}}]

因为上面代码中的$unwind操作，所以有很多"_id: sensor-2“。Quest的问题是: 1.有一个"intensitas“值，如何从所有对象中定义所有"intensitas”？2.如何实现对nodeJs的查询，因为这是mongodb的"ISODate“格式，因为当我在NodeJs中尝试"ISODate is $avg”时。

Answer 1

1-您可以使用$group中提供的$avg，但$group中的id为空。( $project中也提供了$avg)

Answer 2

最后，我可以做我想做的事情，我使用以下代码：

db.getCollection('lampus').aggregate([
{
  $unwind: '$data'
},
{
$match: {_id: "sensor-2",
  'data.tanggal': {
    $gt: (new Date(new ISODate()-1*1000*60*60*24))
  }
}
},

{
$sort: {
  'data.tanggal': 1
}
},
{
   $group:
     {
       _id: "$_id",
       RataInten: { $avg: { $multiply: [ "$data.sensor.intensitas" ] } },
       RataArus: { $avg: { $multiply: [ "$data.sensor.arus" ] } },
     }
 },
 {$project: {data:[{arus :"$RataArus",intensitas :"$RataInten"}]}},
 { $out : "3hari" }, 

 ])

在{ $out："3hari“}上，这是创建名为"3hari”的集合的新集合，我得到了这个：

{
"_id" : "sensor-2",
"data" : [ 
    {
        "arus" : 0.1,
        "intensitas" : 5.0,
        "today" : ISODate("2018-08-05T15:08:17.513+07:00")
    }
]
}

这就是我想要的，但我遇到了问题，我需要更多的"data“数组，正如我所期望的：

{
"_id" : "sensor-2",
"data" : [ 
    {
        "arus" : 0.1,
        "intensitas" : 5.0,
        "today" : ISODate("2018-08-05T15:08:17.513+07:00")
    },
    {
        "arus" : 0.1,
        "intensitas" : 8.0,
        "today" : ISODate("2018-08-08T15:08:17.513+07:00")
    },
    {
        "arus" : 0.1,
        "intensitas" : 9.0,
        "today" : ISODate("2018-08-12T15:08:17.513+07:00")
    }
]
}

是的，我需要更新数据数组，并且有更多的数组...