如何使用 MongoDB 聚合从嵌套的 Object 中提取 Object

Question

I have data in the form of array of objects, Objects contain review and its key value pair and it has reviewDetail. Following is the data

[
    {
        "review": {
            "reviewDetail": {
                "title": "review 2",
                "description": "this is description",
                "file": [
                    "1659414826665-cropped-cropped-logo-e1620197043895-2.png.png"
                ],
                "viewed": 0,
                "isDeleted": true,
                "_id": "62e8a92a0c6e7159a7b934d8",
                "createdAt": "2022-08-02T04:33:46.677Z",
                "updatedAt": "2022-08-02T04:37:28.213Z"
            }
        }
    },
    {
        "review": {
            "reviewDetail": {
                "title": "review 1",
                "description": "this is description of review",
                "file": [
                    "1659414880490-cropped-cropped-logo-e1620197043895-2.png.png"
                ],
                "viewed": 0,
                "isDeleted": true,
                "_id": "62e8a9600c6e7159a7b934df",
                "createdAt": "2022-08-02T04:34:40.499Z",
                "updatedAt": "2022-08-06T12:44:04.633Z"
            }
        }
    },
    {
        "review": {
            "reviewDetail": {
                "title": "review 1",
                "description": "this is description of review",
                "file": [],
                "viewed": 0,
                "isDeleted": true,
                "_id": "62ee5e76e9934990d6911e21",
                "createdAt": "2022-08-06T12:28:38.457Z",
                "updatedAt": "2022-08-06T13:24:03.074Z"
            }
        }
    }
]

i want to extract reviewDetails in the array: following is the desired result

[
              {
                "title": "review 2",
                "description": "this is description",
                "file": [
                    "1659414826665-cropped-cropped-logo-e1620197043895-2.png.png"
                ],
                "viewed": 0,
                "isDeleted": true,
                "_id": "62e8a92a0c6e7159a7b934d8",
                "createdAt": "2022-08-02T04:33:46.677Z",
                "updatedAt": "2022-08-02T04:37:28.213Z"
            },
            {
                "title": "review 1",
                "description": "this is description of review",
                "file": [
                    "1659414880490-cropped-cropped-logo-e1620197043895-2.png.png"
                ],
                "viewed": 0,
                "isDeleted": true,
                "_id": "62e8a9600c6e7159a7b934df",
                "createdAt": "2022-08-02T04:34:40.499Z",
                "updatedAt": "2022-08-06T12:44:04.633Z"
            },
             {
                "title": "review 1",
                "description": "this is description of review",
                "file": [],
                "viewed": 0,
                "isDeleted": true,
                "_id": "62ee5e76e9934990d6911e21",
                "createdAt": "2022-08-06T12:28:38.457Z",
                "updatedAt": "2022-08-06T13:24:03.074Z"
            }
]

I tried to extract in particular pattern using Javascript in node js but needed using aggregation pipeline

Answer 1

You can simply use this to achieve your desired output

collectionName.aggregate([
   {
     $replaceRoot:{ newRoot:"$review.reviewDetail" }
   }    
])