MongoDB 聚合 Shell 脚本到 MongoC# 驱动程序

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连接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方法，（未使用聚合）

注意：修剪此代码以适合 public 问答网站。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

根据给定的评论进行编辑

如果您可以使用 AsQueryable()，您可以获得如下值：

var dbResult = from ticket in ticketsCollection.AsQueryable()
               where ticket.TicketProjectID == 49
               select new 
               {
                   TicketProjectID = ticket.TicketProjectID,
                   TicketID = ticket.TicketID,
                   ConcatValue = ticket.Status + " - " + ticket.Name
               };

以后你可以这样做：

var result = from dbr in dbResult
             where dbr.ConcatValue.Contains("something") //or
             where dbr.ConcatValue.StartsWith("something")//or you can use regex
             select dbr;

Note: For some reason both Status and Name properties from type Ticket need to be of a type String for concatenation to work since mongo driver won't recognize the call to ToString() from some other type.

如果您想连接一些其他类型的属性，您可以从数据库中单独获取它们，而不是在本地连接它们。

note, i'm not that good with mongo shell i could mess something up but you can see in which way you could go

或者你可以这样写你的 shell 命令并将它放在一个字符串中：

var command = @"db.Tickets.aggregate(
[
    { $project: { TicketProjectID:1, TicketID:1, concatValue: { $concat: [ "$Status", " - ", "$Name" ] } } },
    { $match : { TicketProjectId : 49, concatValue : { $regex : /mysearchkey/i } } }
],
{ allowDiskUse : true }
);";

然后使用 MongoDatabase.

中的 RunCommandAsync 方法在 c# 中执行它

var result = await mongoDatabase.RunCommandAsync<BsonDocument>(BsonDocument.Parse(command));

Answer 2

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;

MongoDB 聚合 Shell 脚本到 MongoC# 驱动程序

MongoDB aggregation Shell script to MongoC# Driver

c#

shell

mongodb

mongo-shell

mongodb-.net-driver