我在 MongoDB 数据库中捕获了一些事件数据,其中一些事件成对发生。
例如:DOOR_OPEN 和 DOOR_CLOSE 是成对发生的两个事件
事件集合:
{ _id: 1, name: "DOOR_OPEN", userID: "user1", timestamp: t }
{ _id: 2, name: "DOOR_OPEN", userID: "user2", timestamp: t+5 }
{ _id: 3, name: "DOOR_CLOSE", userID: "user1", timestamp:t+10 }
{ _id: 4, name: "DOOR_OPEN", userID: "user1", timestamp:t+30 }
{ _id: 5, name: "SOME_OTHER_EVENT", userID: "user3", timestamp:t+35 }
{ _id: 6, name: "DOOR_CLOSE", userID: "user2", timestamp:t+40 }
...
假设记录按时间戳排序,则“user1”的 _id: 1 和 _id: 3 是一对。“user2”的 _id: 2 和 _id: 6 是一对。
我想获取每个用户的所有这些 DOOR_OPEN 和 DOOR_CLOSE 对,并计算平均持续时间等。门已被每个用户打开。
这可以使用聚合框架来实现吗?
最佳答案
您可以使用 $lookup
和 $group 来实现此目的。
db.getCollection('TestColl').aggregate([
{ $match: {"name": { $in: [ "DOOR_OPEN", "DOOR_CLOSE" ] } }},
{ $lookup:
{
from: "TestColl",
let: { userID_lu: "$userID", name_lu: "$name", timestamp_lu :"$timestamp" },
pipeline: [
{ $match:
{ $expr:
{ $and:
[
{ $eq: [ "$userID", "$$userID_lu" ] },
{ $eq: [ "$$name_lu", "DOOR_OPEN" ]},
{ $eq: [ "$name", "DOOR_CLOSE" ]},
{ $gt: [ "$timestamp", "$$timestamp_lu" ] }
]
}
}
},
],
as: "close_dates"
}
},
{ $addFields: { "close_time": { $arrayElemAt: [ "$close_dates.timestamp", 0 ] } } },
{ $addFields: { "time_diff": { $divide: [ { $subtract: [ "$close_time", "$timestamp" ] }, 1000 * 60 ]} } }, // Minutes
{ $group: { _id: "$userID" ,
events: { $push: { "eventId": "$_id", "name": "$name", "timestamp": "$timestamp" } },
averageTimestamp: {$avg: "$time_diff"}
}
}
])
示例数据:
[
{ _id: 1, name: "DOOR_OPEN", userID: "user1", timestamp: ISODate("2019-10-24T08:00:00Z") },
{ _id: 2, name: "DOOR_OPEN", userID: "user2", timestamp: ISODate("2019-10-24T08:05:00Z") },
{ _id: 3, name: "DOOR_CLOSE", userID: "user1", timestamp:ISODate("2019-10-24T08:10:00Z") },
{ _id: 4, name: "DOOR_OPEN", userID: "user1", timestamp:ISODate("2019-10-24T08:30:00Z") },
{ _id: 5, name: "SOME_OTHER_EVENT", userID: "user3", timestamp:ISODate("2019-10-24T08:35:00Z") },
{ _id: 6, name: "DOOR_CLOSE", userID: "user2", timestamp:ISODate("2019-10-24T08:40:00Z") },
{ _id: 7, name: "DOOR_CLOSE", userID: "user1", timestamp:ISODate("2019-10-24T08:50:00Z") },
{ _id: 8, name: "DOOR_OPEN", userID: "user2", timestamp:ISODate("2019-10-24T08:55:00Z") }
]
结果:
/* 1 */
{
"_id" : "user2",
"events" : [
{
"eventId" : 2.0,
"name" : "DOOR_OPEN",
"timestamp" : ISODate("2019-10-24T08:05:00.000Z")
},
{
"eventId" : 6.0,
"name" : "DOOR_CLOSE",
"timestamp" : ISODate("2019-10-24T08:40:00.000Z")
},
{
"eventId" : 8.0,
"name" : "DOOR_OPEN",
"timestamp" : ISODate("2019-10-24T08:55:00.000Z")
}
],
"averageTimestamp" : 35.0
}
/* 2 */
{
"_id" : "user1",
"events" : [
{
"eventId" : 1.0,
"name" : "DOOR_OPEN",
"timestamp" : ISODate("2019-10-24T08:00:00.000Z")
},
{
"eventId" : 3.0,
"name" : "DOOR_CLOSE",
"timestamp" : ISODate("2019-10-24T08:10:00.000Z")
},
{
"eventId" : 4.0,
"name" : "DOOR_OPEN",
"timestamp" : ISODate("2019-10-24T08:30:00.000Z")
},
{
"eventId" : 7.0,
"name" : "DOOR_CLOSE",
"timestamp" : ISODate("2019-10-24T08:50:00.000Z")
}
],
"averageTimestamp" : 15.0
}
关于MongoDB Aggregate如何配对相关记录进行处理,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/58535108/