Mongodb 聚合条件和查询值

Question

我是 mongodb 的新手。我需要知道如何查询项目以设置为聚合值

数据

[
  {
    "_id" : "11111",
    "parent_id" : "99",
    "name" : "AAAA"
  },
  {
    "_id" : "11112",
    "parent_id" : "99",
    "name" : "BBBB"
  },
  {
    "_id" : "11113",
    "parent_id" : "100",
    "name" : "CCCC"
  },
  {
    "_id" : "11114",
    "parent_id" : "99",
    "name" : "DDDD"
  }
]

蒙哥壳

假设 $check 为假

db.getCollection('test').aggregate(
  [
    {
      "$group": {
        "_id": "$id",
        //...,
        "item": {
          "$last": {
            "$cond": [
              {"$eq": ["$check", true]},
              "YES",
              * * ANSWER **,
              }
            ]
          }
        },
      }
  ]
)

所以我需要项目的结果是所有名称都包含与数组字符串相同的 parent_id

期待结果

[
  {
    "_id" : "11111",
    "parent_id" : "99",
    "name" : "AAAA",
    "item" : ["AAAA","BBBB","DDDD"]
  },

  {
    "_id" : "11112",
    "parent_id" : "99",
    "name" : "BBBB",
    "item" : ["AAAA","BBBB","DDDD"]
  },

  {
    "_id" : "11113",
    "parent_id" : "100",
    "name" : "CCCC",
    "item" : ["CCCC"]
  },

  {
    "_id" : "11114",
    "parent_id" : "99",
    "name" : "DDDD",
    "item" : ["AAAA","BBBB","DDDD"]
  }
]

Answer 1

试试这个..

Sample live demo

db.collection.aggregate([
  {
    "$group": {
      "_id": "$parent_id",
      "item": {
        "$push": "$name"
      },
      "data": {
        "$push": {
          "_id": "$_id",
          "name": "$name"
        }
      }
    }
  },
  {
    "$unwind": "$data"
  },
  {
    "$project": {
      "_id": "$data._id",
      "parent_id": "$_id",
      "name": "$data.name",
      "item": 1
    }
  }
])