按年份在mongodb上分组

时间:2020-05-05 15:49:00

标签: mongodb mongodb-query aggregation-framework

我的文档以这种方式存储,不,我无法更改它们:

{
        "_id" : ObjectId("5ea773f219d60c4f1629203a"),
        "direction" : 135,
        "latitude" : -3.744851,
        "longitude" : -38.545571,
        "metrictimestamp" : "20180201025959",
        "odometer" : 55697826,
        "routecode" : 0,
        "speed" : 3,
        "deviceid" : 134680,
        "vehicleid" : 32040
}

我需要从这个“ metrictimestamp”中按车辆识别号分组,并且只需要一年中的某一天,并计算具有相同车辆和日期,想法的多少文件?

1 个答案:

答案 0 :(得分:1)

我想说您的metrictimestamp可能包含前几个字符20180201作为YYYYMMDD,因此使用$substrbytes进行聚合可以从字符串中获取月,日,年。尝试以下查询:

db.collection.aggregate([
  {
    $addFields: {
      day: { $toInt: { $substrBytes: [ "$metrictimestamp", 6, 2 ] } }, // $toInt can be optional
      month: { $toInt: { $substrBytes: [ "$metrictimestamp", 4, 2 ] } },
      year: { $toInt: { $substrBytes: [ "$metrictimestamp", 0, 4 ] } }
    }
  },
  {
    $group: {
      _id: { vehicleid: "$vehicleid", day: "$day", year: "$year" },
      count: { $sum: 1 }
    }
  }
])

测试: mongoplayground