将嵌入文档转换为mongodb中的单独文档答案

【问题标题】：Convert embedded documents into separate documents in mongodb将嵌入文档转换为mongodb中的单独文档
【发布时间】：2021-12-27 13:14:49
【问题描述】：

我有以下文件。

[
  {
    "content": {
      "abc123": {
        "_id": "abc123",
        "total": 189,
        "published": 189,
        "created": 0,
        "approved": 0,
        "rejected": 0,
        "sent_for_approval": 0
      },
      "abc124": {
        "_id": "abc124",
        "total": 1911,
        "published": 1899,
        "created": 10,
        "approved": 2,
        "rejected": 0,
        "sent_for_approval": 0
      }
    }
  },
  {
    "content": {
      "abc124": {
        "_id": "abc124",
        "total": 1911,
        "published": 1899,
        "created": 10,
        "approved": 2,
        "rejected": 0,
        "sent_for_approval": 0
      }
    }
  }
]

如何将这个键值对对象转换成单独的文档，如下所示，不重复enter code here:

[
  {
    "_id": "abc123",
    "total": 189,
    "published": 189,
    "created": 0,
    "approved": 0,
    "rejected": 0,
    "sent_for_approval": 0
  },
  {
    "_id": "abc124",
    "total": 1911,
    "published": 1899,
    "created": 10,
    "approved": 2,
    "rejected": 0,
    "sent_for_approval": 0
  }
]

【问题讨论】：

标签： mongodb mongodb-query aggregation-framework

【解决方案1】：

查询

将对象转换为数组
展开并替换根（因此每个嵌入的文档都是一个单独的根文档）
按键分组，只保留第一个删除重复项
替换 root 以获得预期的输出

Test code

aggregate(
[{"$set":{"content":{"$objectToArray":"$content"}}},
 {"$unwind":"$content"},
 {"$replaceRoot":{"newRoot":"$content"}},
 {"$group":{"_id":"$k", "doc":{"$first":"$v"}}},
 {"$replaceRoot":{"newRoot":"$doc"}}])

【讨论】：