Question

我从以下代码获得数据：

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"}}]

“ _ id：sensor-2”太多，因为上面的代码中$ unwind操作。任务是： 1.有一个“ intensitas”值，如何从所有对象中平均所有“ intensitas”？ 2.我如何实现对NodeJ的查询，因为那是mongodb中的“ ISODate”格式，因为当我尝试在nodeJ中使用“ ISODate未定义”时。

Answer 1

1-您可以使用$ group中可用的$ avg，而$ group中的ID为空。（$ avg在$ project中也可用）

Answer 2

最后我可以做我想做的，我使用这段代码：

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，即创建名为“ 3hari”的集合tha的新内容，

{
"_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，但是我遇到了问题，我需要更多的“数据”数组，就像我期望的那样：

{
"_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，并且具有更多数组...

来自多个对象的MongoDb $ avg

2 个答案: