node.js - MongoDB:按两个具有不同值的字段重新分组

Question

我在 Typescript 中创建了一个 Nodejs 应用程序。我想按两个字段“one_id”和“two_id”以及指定的 one_id 值对文档进行分组。

这是我收集的数据:

{  
   "_id":"5a8b2953007a1922f00124fd",
   "one_id":"307973260186877954",
   "two_id":"415228402765660181"
}
{  
   "_id":"5a8b29a3007a1922f00124fe",
   "one_id":"415228402765660181",
   "two_id":"307973260186877954"
}
{  
   "_id":"5a8c119bf6ba49302c3ef67e",
   "one_id":"394199132195127306",
   "two_id":"270131587092316161"
}
{  
   "_id":"5a8c11a4f6ba49302c3ef67f",
   "one_id":"270131587092316161",
   "two_id":"394199132195127306"
}
{  
   "_id":"5a8c33132a182308a836bc1c",
   "one_id":"307973260186877954",
   "two_id":"397036401075552256"
}
{  
   "_id":"5a8c33242a182308a836bc1d",
   "one_id":"397036401075552256",
   "two_id":"307973260186877954"
}

如果我想与 one_id="307973260186877954"配对，异常(exception)的结果将是:(必须有另一个包含“反向”字段内容的文档)

{  
   "_id":"5a8b2953007a1922f00124fd",
   "one_id":"307973260186877954",
   "two_id":"415228402765660181"
}
{  
   "_id":"5a8b29a3007a1922f00124fe",
   "one_id":"415228402765660181",
   "two_id":"307973260186877954"
}
{  
   "_id":"5a8c33132a182308a836bc1c",
   "one_id":"307973260186877954",
   "two_id":"397036401075552256"
}
{  
   "_id":"5a8c33242a182308a836bc1d",
   "one_id":"397036401075552256",
   "two_id":"307973260186877954"
}

不知道你是否明白我的意思。

谢谢你，希望有人能理解我!

Answer 1

您可以使用 $lookup 自连接行并在匹配时输出文档，并使用排除的 $project 删除连接的字段。

db.col.aggregate([
  {"$lookup":{
    "from":col,
    "localField":"one_id",
    "foreignField":"two_id",
    "as":"onetwo"
  }},
  {"$lookup":{
    "from":col,
    "localField":"two_id",
    "foreignField":"one_id",
    "as":"twoone"
  }},
  {"$match":{"onetwo.0":{"$exists":true}, "twoone.0":{"$exists":true}}},
  {"$project":{"onetwo":0,"twoone":0}}
])