如何在golang mgo.v2 liabry中使用MongoDB获取聚合Pipline结果

Question

问题背景是我想使用golang mgo.v2 liabary从MongoDB数据中检索聚合数据。

我有一个集合数据集，如下所示。集合名称是useragents

Event event = new Event()
{
    Summary = "Appointment",
    Location = "Somewhere",
    Start = new EventDateTime() {
        DateTime = new DateTime("2016-10-14T10:00:00")
        TimeZone = "Europe/Warsaw"
    },
    End = new EventDateTime() {
        DateTime = new DateTime("2016-10-14T11:00:00")
        TimeZone = "Europe/Warsaw"
    },
    Recurrence = new String[] {
        "RRULE:FREQ=YEARLY;BYMONTHDAY=14;BYMONTH=10"
    },
    Attendees = new List<EventAttendee>()
    {
        new EventAttendee() { Email: "attendeeEmail" },
        // ...
    }
};

Event recurringEvent = service.Events.Insert(event, "primary").Fetch();

Console.WriteLine(recurringEvent.Id);

我已经通过堆栈溢出社区的帮助解决了我想要的MongoDB shell脚本。但是当我使用mgo.v2库在golang中实现它时，我感到很麻烦。

这是mongodb shell脚本

{
    "_id" : ObjectId("57f940c4932a00aba387b0b0"),
    "tenantID" : 1,
    "date" : "2016-10-09 00:23:56",
    "venueList" : [
        {
            "id" : “VID1212”,
            "sum" : [
                {
                      "name" : "linux",
                      "value" : 12
                },
                {
                    "name" : "ubuntu",
                    "value" : 4
                }
            ],
            “ssidList” : [    // this is list of ssid’s in venue
                {
                    "id" : “SSID1212”,
                    "sum" : [
                        {
                            "name" : "linux",
                            "value" : 8
                        },
                        {
                            "name" : "ubuntu",
                            "value" : 6
                        }
                    ],
                    “macList” : [  // this is mac list inside particular ssid  ex: this is mac list inside the SSID1212
                        {
                            "id" : “12:12:12:12:12:12”,
                            "sum" : [
                                {
                                    "name" : "linux",
                                    "value" : 12
                                },
                                {
                                    "name" : "ubuntu",
                                    "value" : 1
                                }
                            ]
                        }
                    ]
                }
            ]
        },
        {
            "id" : “VID4343”,
            "sum" : [
                {
                     "name" : "linux",
                     "value" : 2
                }
            ],
            "ssidList" : [
                {
                    "id" : “SSID4343”,
                    "sum" : [
                        {
                            "name" : "linux",
                            "value" : 2
                        }
                    ],
                    "macList" : [
                        {
                            "id" : “43:43:43:43:43:34”,
                            "sum" : [
                                {
                                    "name" : "linux",
                                    "value" : 2
                                }
                            ]
                        }
                    ]
                }
            ]
        }
    ]
}

请访问question background

我实现golang代码如下

db.useragents.aggregate([
    { "$match": { "venueList.id": { "$in": ["VID1212", "VID4343"] } } },
    { "$unwind": "$venueList" },
    { "$match": { "venueList.id": { "$in": ["VID1212", "VID4343"] } } },
    { "$unwind": "$venueList.sum" },    
    { 
        "$group": {
            "_id": "$venueList.sum.name",
            "count": { "$sum": "$venueList.sum.value" }
        }
    },
    { 
        "$group": {
            "_id": null,
            "counts": {
                "$push": {
                    "name": "$_id",
                    "value": "$count"
                }
            }
        }
    }
])

我创建了一个pipline并将其提供给pipe.All（）但是从func GetBrowserStats(constrains models.Constrains) ([]bson.M, error) { session := commons.GetMongoSession() defer session.Close() var col = session.DB("analytics").C("useragents") pipeline1 := bson.M{ "$match": bson.M{ "venueList.id": bson.M{ "$in": []string{"VID1212", "VID4343"}, }, }, } pipeline2 := bson.M{ "$unwind": "$venueList", } pipeline3 := bson.M{ "$match": bson.M{ "venueList.id": bson.M{ "$in": []string{"VID1212", "VID4343"}, }, }, } pipeline4 := bson.M{ "$unwind": "$venueList.sum", } pipeline5 := bson.M{ "$group": bson.M{ "_id": "$venueList.sum.name", "count": bson.M{ "$sum": "$venueList.sum.value", }, }, } pipeline6 := bson.M{ "$group": bson.M{ "_id": bson.NewObjectId(), "counts": bson.M{ "$push": bson.M{ "name": "$_id", "value": "$count", }, }, }, } all := []bson.M{pipeline1, pipeline2, pipeline3, pipeline4, pipeline5, pipeline6} pipe := col.Pipe(all) result := []bson.M{} err := pipe.All(&result) println(result[0]) if err != nil { println(err.Error()) errMsg := "Error occourred while getting dashboard configs from mongo stack:" + err.Error() log.Error() return result, errors.New(errMsg) } return result, nil } 变量返回null结果。

我想在result

中返回以下对象

result

Answer 1

最后我找到了解决方案。我想与stackoverflow社区分享。

我推荐这个：google group answer

 session := commons.GetMongoSession()
    defer session.Close()

    pipeline := []bson.D{
        bson.D{
            {"$match",
                bson.M{
                    "venueList.id": bson.M{"$in": []string{"VID1212", "VID4343"}},
                },
            },
        },
        bson.D{
            {"$unwind", "$venueList"},
        },
        bson.D{
            {"$match",
                bson.M{
                    "venueList.id": bson.M{"$in": []string{"VID1212", "VID4343"}},
                },
            },
        },
        bson.D{
            {"$unwind", "$venueList.sum"},
        },
        bson.D{
            {"$group",

                bson.M{
                    "_id": "$venueList.sum.name",
                    "count": bson.M{
                        "$sum": "$venueList.sum.value",
                    },
                },
            },
        },
        bson.D{
            {"$group",
                bson.M{
                    "_id": bson.NewObjectId(),
                    "counts": bson.M{
                        "$push": bson.M{
                            "name":  "$_id",
                            "value": "$count",
                        },
                    },
                },
            },
        },
    }

    query := bson.D{
        {"aggregate", "useragents"}, // useragents is a collection name
        {"pipeline", pipeline},
    }

    var res interface{}
    err := session.DB("analytics").Run(query, &res)
    if err != nil {
        println(err.Error())
    } else {
        println(res)
    }