c# - MongoDB 聚合 Shell 脚本到 MongoC# Driver

Question

如何将此 Mongo Shell 脚本转换为 MongoDB C# 驱动程序？

var myItems = []

var myCursor = db.Tickets.aggregate(
   [
      { $match : { TicketProjectID : 49 } },
      { $project: { TicketProjectID:1, TicketID:1, concatValue: { $concat: [ "$Status", " - ", "$Name" ] } } }
    // I will have a list of fields that I need to concatenate at run time. So C# query should support concatenation for "N" number of fields at run-time.
      //{ $group: { _id: null, count: { $sum: 1 } } }

   ],
      { allowDiskUse: true }
)

   //This seems like a ugly performance approach when we are working against 100k results with above match
     while (myCursor.hasNext()) {
         var item = myCursor.next();
         if(item.concatValue.search(/mysearchkey/i) > -1)
             {
                myItems.push(item.TicketID)
             }
    }    
    myItems

或者是否有更好的方法在串联投影中进行字符串搜索而不是在游标中进行 foreach，因为某些查询可能会获得 50k 条记录。

这是我到目前为止尝试过的，(不使用聚合)

注意:修剪此代码以适合公共(public)问答站点。所以请将其视为伪代码

 var tickets = ticketsCollection.FindSync(filter).ToList();
                string concatinatedValue = string.Empty;
                foreach (var ticket in tickets)
                {
                    foreach (var field in customFieldsForThisProject)
                        concatinatedValue += ticket[field.Replace(" ", "_")];

                  if(concatinatedValue.StripHtml().contains("MysearchWord"))
                 {
                   TikectIdList.Add(ticket["TicketID"])
                 }
                }

Answer 1

感谢@Nikola.Lukovic，在他的伪代码上工作，我想出了这个可行的解决方案。

方法一:完全使用 C# 驱动程序

var ticketsCollection = _mongoConnect.Database.GetCollection<BsonDocument>("Tickets");

            var dbResult = from ticket in ticketsCollection.AsQueryable()
                select new
                {
                    TicketProjectID = ticket["TicketProjectID"],
                    TicketID = ticket["TicketID"],
                    ConcatValue = ticket["Status"] + (string) ticket["Name"]
                };
            var matches = from dbr in dbResult
                where dbr.ConcatValue.Contains(searchKey)
                where dbr.ConcatValue.StartsWith(searchKey)
                select dbr;

This will not work for my scenario as fields I am trying to concatenate are if type string, but $add will only work with numeric and date types.

方法二:使用RunCommand 并直接传递 Shell 命令。 这适用于所有数据类型。也能满足我的需要。

        var projectCommand =
            BsonDocument.Parse(
                "{ $project: { _id: -1, TicketProjectID:1, TicketID:1, concatValue: { $concat: [ \"$Status\", \" - \", \"$Name\" ] } } }");
        var matchCommand =
            BsonDocument.Parse("{ $match: {concatValue: { $regex: '" + searchKey + "', $options: 'i'} } }");

        var pipeline = new[] {projectCommand, matchCommand};
        var result = ticketsCollection.Aggregate<BsonDocument>(pipeline).ToList();
        if (result.Count > 0)
            return result.Select(x => (int)x["TicketID"]).ToList();
        return null;