golang 中mongodb利用时间戳进行分组统计

话不多说，直接先上代码：

// StatGameActive 游戏活跃人数
func StatGameActive(start, end int64, gameID string) map[string]int {
    type resp struct {
        Date    string `bson:"date"`
        Count   int    `bson:"count"`
    }
    var (
        m    career.GameLoginLog
        data []resp
        rs   = make(map[string]int)
    )
    where := bson.M{"created_at": bson.M{"$gte": start, "$lte": end}, "game_id": gameID}
    dateBson := bson.M{"$dateToString": bson.M{"format": "%Y-%m-%d", "date": bson.M{"$toDate": bson.M{"$add": bson.A{ 28800000, bson.M{"$multiply": bson.A{"$created_at", 1000}} } } }}}
    pipe:= []bson.M{
        {"$match": where},
        {"$project": bson.M{"date": dateBson, "user_id": 1} },
        {"$group": bson.M{"_id":bson.M{"date": "$date", "user": "$user_id"}}},
        {"$group": bson.M{"_id": "$_id.date",  "count": bson.M{"$sum": 1}}},
        {"$project": bson.M{"date": "$_id","count":1, "_id": 0}},
    }
    _ = mongo.Collection(m).AggregateWithError(pipe, &data)
    for _, v := range data {
        rs[v.Date] = v.Count
    }
    return rs
}

bson.M{"$toDate": bson.M{"$add": bson.A{ 28800000, bson.M{"$multiply": bson.A{"$created_at", 1000}} } }$created_at$adddate$toDate

另外：

$group$project