Mongoose pluck document array

Question

I have a document like this:

I have a schema design like this, I'm using mongoose-paginate-v2:

 const options = {
        select: 'files',
        lean: true,
        offset,
        limit
    };
    
    const data = Message.paginate(
        { conversation_id: conversationId, 'files.category': { "$in" : category } },
        options,
    );
    
    return data;

This is my response data:

    [
                  {
        "_id": "628472b3ef39fbb8bb655317",
        "files": [
            {
                "src": "U21102500080/2022/5/images/1652847282675-pexels_02.jpeg",
                "name": "pexels_02.jpeg",
                "extension": "jpeg",
                "size": 25708,
                "category": "image",
                "_id": "628472b3ef39fbb8bb655318"
            },
            {
                "src": "U21102500080/2022/5/images/1652847282704-pexels_03.jpeg",
                "name": "pexels_03.jpeg",
                "extension": "jpeg",
                "size": 107748,
                "category": "image",
                "_id": "628472b3ef39fbb8bb655319"
            },
            {
                "src": "U21102500080/2022/5/images/1652847282704-pexels_01.jpeg.jpeg",
                "name": "pexels_01.jpeg.jpeg",
                "extension": "jpeg",
                "size": 22364,
                "category": "image",
                "_id": "628472b3ef39fbb8bb65531a"
            }
        ],
        "id": "628472b3ef39fbb8bb655317"
    },
    {
        "_id": "628702c293b660628e95124d",
        "files": [
            {
                "src": "c6ed8c14-bcec-4739-bdf2-2392c7d15318/2022/5/images/1653015230055-pexels-photo-11427585.jpeg",
                "name": "pexels-photo-11427585.jpeg",
                "extension": "jpeg",
                "size": 17000,
                "category": "image",
                "_id": "628702c293b660628e95124e"
            },
            {
                "src": "c6ed8c14-bcec-4739-bdf2-2392c7d15318/2022/5/images/1653015230098-chen-sithyfong-1fSRYz5QpSE-unsplash.jpeg",
                "name": "chen-sithyfong-1fSRYz5QpSE-unsplash.jpeg",
                "extension": "jpeg",
                "size": 174722,
                "category": "image",
                "_id": "628702c293b660628e95124f"
            },
            {
                "src": "c6ed8c14-bcec-4739-bdf2-2392c7d15318/2022/5/images/1653015230098-screen-post-EC5kTElGfNs-unsplash.jpeg",
                "name": "screen-post-EC5kTElGfNs-unsplash.jpeg",
                "extension": "jpeg",
                "size": 160266,
                "category": "image",
                "_id": "628702c293b660628e951250"
            }
        ],
        "id": "628702c293b660628e95124d"
    },
    {
        "_id": "628702fa93b660628e951275",
        "files": [
            {
                "src": "U21102500080/2022/5/images/1653015288963-2022-01-26 16.58.29.jpg",
                "name": "2022-01-26 16.58.29.jpg",
                "extension": "jpg",
                "size": 34576,
                "category": "image",
                "_id": "628702fa93b660628e951276"
            },
            {
                "src": "U21102500080/2022/5/images/1653015288968-2022-01-26 16.58.20.jpg",
                "name": "2022-01-26 16.58.20.jpg",
                "extension": "jpg",
                "size": 31982,
                "category": "image",
                "_id": "628702fa93b660628e951277"
            },
            {
                "src": "U21102500080/2022/5/images/1653015288968-2022-01-26 16.58.24.jpg",
                "name": "2022-01-26 16.58.24.jpg",
                "extension": "jpg",
                "size": 119198,
                "category": "image",
                "_id": "628702fa93b660628e951278"
            }
        ],
        "id": "628702fa93b660628e951275"
    },
 ]

But I want this response data:

[ { "src": "", "name": "", "extension": "", "size": 0, "category": "", "_id": "628472b3ef39fbb8bb655318" }, { "src": "", "name": "", "extension": "", "size": 0, "category": "", "_id": "628472b3ef39fbb8bb655319" }, { "src": "", "name": "", "extension": "", "size": 0, "category": "", "_id": "628472b3ef39fbb8bb65531a" }, { "src": "", "name": "", "extension": "", "size": 0, "category": "", "_id": "628702c293b660628e95124e" } ]

Answer 1

 const options = {
        select: 'files',
        lean: true,
        offset,
        limit
    };
    
    let data = Message.paginate(
        { conversation_id: conversationId, 'files.category': { "$in" : category } },
        options,
    );
    data = data.reduce((prev,curr) => [...prev.files, ...curr.files], [] )
    return data;