MongoDB - 将数组拆分为多个文档并用数组的对象替换现有文档

Question

我收集了一个大的 json 文档，如下所示：

\n\n

{\n  "_id": {\n    "$oid": "5e7a50e7f1d41b3ea05aa46e"\n  },\n  "response": {\n    "count": 2,\n    "items": [\n      {\n        "id": 1,\n        "first_name": "Unknown",\n        "last_name": "Unknown",\n        "is_closed": false,\n        "can_access_closed": true,\n        "photo": "1.jpg",\n        "track_code": "d9e2ca2eG4GbHAQSwz8Ne4WBiVx"\n      },\n      {\n        "id": 2,\n        "first_name": "Lorem",\n        "last_name": "Ipsum",\n        "is_closed": false,\n        "can_access_closed": true,\n        "photo": "2.jpg",\n        "track_code": "23f1219a7j1xyWba69jz7p"\n      }\n    ]\n  }\n}\n

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如何按集合中的各个对象（例如按项目中的 id）拆分“项目”？\n因此我想要这样的东西：

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对象#1

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{\n  "_id": {\n    "$oid": "5e7a50e7f1d41b3ea05aa46e"\n  },\n  "id": 1,\n  "first_name": "Unknown",\n  "last_name": "Unknown",\n  "is_closed": false,\n  "can_access_closed": true,\n  "photo": "1.jpg",\n  "track_code": "d9e2ca2eG4GbHAQSwz8Ne4WBiVx"\n}\n

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对象#2

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{\n  "_id": {\n    "$oid": "ae2a40e7ffd41b3ea05aa46e"\n  },\n  "id": 2,\n  "first_name": "Lorem",\n  "last_name": "Ipsum",\n  "is_closed": false,\n  "can_access_closed": true,\n  "photo": "2.jpg",\n  "track_code": "23f1219a7j1xyWba69jz7p"\n}\n

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我无法理解如何在文档中查找此内容。

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Answer 1

您可以尝试下面的查询，这样您的结果中的文档数量可能会多于集合中的实际数量，因为我们正在爆炸项目数组：

db.collection.aggregate([
  /** Adds '_id' field to each object inside items array, this can be done after 'unwind',
   *  if it's done after 'unwind' no.of docs to be iterated in 'unwind' is more, So better be done as first stage*/
  {
    $addFields: {
      "response.items._id": "$_id"
    }
  },
  /** Unwind items array, will exclude docs where items is not an array/doesn't exists */
  {
    $unwind: "$response.items"
  },
  /** Replace 'response.items' object as new root(document) */
  {
    $replaceRoot: {
      newRoot: "$response.items"
    }
  }
])

测试： MongoDB-Playground

参考： 聚合管道