c# - 使用聚合从 mongodb 中的 order by 和 group by 联合选择

Question

我尝试使用 C# 聚合框架将下一个 SQL 查询重写到 mongodb，但我不明白该怎么做。我需要合并一些结果。

SELECT TOP 100 RES.Agent, RES.Type, RES.Opens FROM ((SELECT UA.ClientDomain AS Agent, UA.Type AS Type, COUNT(*) AS Opens 
                                                    FROM tReadConfirm AS RC INNER JOIN tUserAgent AS UA ON RC.UserAgentId = UA.Id
                                                    WHERE RC.UserId = 2654 AND RC.CampaignId = 27442  AND UA.Type = 1
                                                    GROUP BY UA.ClientDomain, UA.Type)
                                                UNION
                                                (SELECT UA.Family AS Agent, UA.Type AS Type, COUNT(*) AS Opens 
                                                    FROM tReadConfirm AS RC INNER JOIN tUserAgent AS UA ON RC.UserAgentId = UA.Id
                                                    WHERE RC.UserId = 2654 AND RC.CampaignId = 27442 AND UA.Type <> 1
                                                    GROUP BY UA.Family, UA.Type)) AS RES
                                                ORDER BY RES.Opens DESC

这是我的开始代码，但它不能满足我的需要

db.analytics.aggregate(
    {
        $match: { UserId: 4749, CampaignId: 93178}
    },
    {
        $group :
        {
            _id : 
            { 
                "Family" : "$userAgent.Family",
                "Type" : "$userAgent.Type",
                "ClientDomain" : "$userAgent.ClientDomain",
            }  ,
            "Opens": 
            {
                 $sum : 1 
            }
         }
     },
     {$sort :{"Opens":-1}}
)

Answer 1

我找到了答案，这是我的工作代码示例。运算符“$cond”帮助了我。

db.analytics.aggregate(

    { 
        $match : { 
            "UserId" : 4790, 
            "CampaignId" : 93178} 
     },
     {
        $group :
        {
            _id : 
            { 
                "Type" : "$userAgent.Type",
                "ClientDomain" : { $cond: { if: { $eq: [ "$userAgent.Type", 1 ] }, then: "$userAgent.ClientDomain", else: "$userAgent.Family" }},
            }  ,
            "Opens": 
            {
                 $sum : 1 
            }
         }
     },
     {
         $sort :{"Opens":-1}
     },
     {
         $limit:10
     }
)