如何创建包含$redact的C#mongodb管道

我正在尝试使用C#驱动程序创建一个mongodb聚合管道,该驱动程序包括修订后的项目.我尝试了如下所示的几种方法,但是在每种情况下,仅执行管道的第一阶段. AppendStage似乎不会追加下一阶段.那么,如何使用C#mongodb驱动程序编写一个后跟项目的项目.请注意,流畅的界面不直接支持编辑,但另一篇文章显示了使用下面的代码来实现这一点,该文章适用于第一阶段.

我正在使用2.4.3版本的C#驱动程序和mongodb版本3.4.4

string redactJson = System.IO.File.ReadAllText(@"redactTest.json");
string projectJson = System.IO.File.ReadAllText(@"projectTest.json");

var collection = Database.GetCollection<BsonDocument>("Forecasts");

var redact = BsonDocument.Parse(redactJson);
var project = BsonDocument.Parse(projectJson);


var aggregatonPipeline = collection.Aggregate();
aggregatonPipeline.AppendStage<BsonDocument>(redact);
aggregatonPipeline.AppendStage<BsonDocument>(project);

var list = aggregatonPipeline.ToList();

或类似的代码

var pipeline = collection.Aggregate().AppendStage<BsonDocument>(redact);
pipeline.AppendStage<BsonDocument>(project);
var list = pipeline.ToList();

我的聚合json看起来像这样

redactTest.json：

{
    $redact: {
       $cond: {
         if: {
             $gt: [{ $size: { "$setIntersection": [ "$tags", ["STLW", "G"]]}}, 0]
         },
         then: "$$DESCEND",
         else: "$$PRUNE"
      }
   }
}

projectTest.json

{
  "$project":
  {
    "_id": 0,
    "title": 1,
    "year": 1,
    "subsections.subtitle": 1,
    "subsections.content":  1 
  }
}

源文件是

{
  _id: 1,
  title: "123 Department Report",
  tags: [ "G", "STLW" ],
  year: 2014,
  subsections: [
    {
      subtitle: "Section 1: Overview",
      tags: [ "SI", "G" ],
      content:  "Section 1: This is the content of section 1."
    },
    {
      subtitle: "Section 2: Analysis",
      tags: [ "STLW" ],
      content: "Section 2: This is the content of section 2."
    },
    {
      subtitle: "Section 3: Budgeting",
      tags: [ "TK" ],
      content: {
      text: "Section 3: This is the content of section3.",
       tags: [ "HCS" ]
     }
   }
 ]
}

解决方法:

collection.Aggregate()公开流利的聚合接口,并通过方法链接将阶段附加到管道中.

就像是

var pipeline= collection.Aggregate().AppendStage<BsonDocument>(redact).AppendStage<BsonDocument>(project);
var list = pipeline.ToList();

一次添加一个阶段时,您的用法将覆盖先前的阶段.