MongoDB find by Id in nested array

Question

My model called Residence

{
    "_id": { "$oid": "5d88dfe45feb4c06a5cfb762" },
    "spaces": [{ 
        "_id": { "$oid": "5d88dfe45feb4c06a5cfb76f" },
        "name": "Building 2",
        "subSpace": [
            {
                "_id": { "$oid": "5d88dfe45feb4c06a5cfb771" },
                "name": "Basement"
            }, 
            {
                "_id": { "$oid": "5d88dfe45feb4c06a5cfb770" }, 
                "name": "Floors" // Get only the name by Id
            }
        ]
    }
}

To find a spaceName by Id (OK)

exports.getSpaceNameById = (spaceId) => {
    return Residence.find({ 'spaces._id': spaceId }, { _id: 0, spaces: { $elemMatch: { _id: spaceId } } })
}

Now I want to have the subSpace name requested by Id.

But my dream would be to have both (query by subSpace Id, for this example : 5d88dfe45feb4c06a5cfb770) : spaceName / subSpaceName only with 1 request.

Thanks for your help.

UPDATE 1

I try this method but the response is an empty array

exports.getSubSpaceNameById = (spaceId) => {
    return Residence.aggregate([
        { $match: {'spaces.subSpace._id': spaceId}},
        { $project: {
            'spaces.subSpace': { $filter: {
                input: '$spaces.subSpace',
                as: 'mySubSpace',
                cond: { $eq: ['$$mySubSpace._id', spaceId]}
            }},
            _id: 0
        }}
    ])
}

To clarify ( [as there is some discussion on this already](https://meta.stackoverflow.com/q/390887/2313887) ) the reason your question is closed is not actually a "suggestion" despite the comment currently automatically added. The question is closed because **I know** from many years of experience that this is indeed the answer. If you get an empty result, then you provided incorrect details. The method demonstrated is indeed correct. Please learn from it. — Neil Lunn, Oct 30 '19 at 09:28

score 0 · Answer 1 · edited Oct 30 '19 at 07:20

0

Try something like this:

find({spaces._id:id})

edited Oct 30 '19 at 07:20

Nikola Lukic

4,001
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answered Oct 30 '19 at 06:09

vicky

415
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score 0 · Answer 2 · answered Oct 30 '19 at 06:11

0

The following should work for you. This query would return the whole document.

By name: db.collection.find({"spaces.subSpace.name": "Basement"})

By _id: db.collection.find({"spaces.subSpace._id": "YOUR_ID"})

answered Oct 30 '19 at 06:11

Shihab

2,641
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Yes I already tried this query but when I have the entire document, how to find the good subSpace name requested ? – Arnaud Lord Sesstyle Oct 30 '19 at 08:48

score 0 · Answer 3 · answered Oct 30 '19 at 06:33

Try this query

   db.testers.aggregate([
    {
        $addFields:{
            "spaces":{
                $map:{
                    "input":"$spaces",
                    "as":"doc",
                    "in":{
                        $mergeObjects:[
                            "$$doc",
                            {
                                "subSpace":{
                                    $filter:{
                                        "input":"$$doc.subSpace",
                                        "as":"sn",
                                        "cond": {
                                        "$and": [
                                            { "$eq": [ "$$sn._id", "5d88dfe45feb4c06a5cfb770" ] },
                                        ]
                                    }

                                }
                            }
                            }
                        ]
                    }
                }
            }
        }
    }
]).pretty()

Thanks but this request returns all documents in the collection — Arnaud Lord Sesstyle, Oct 30 '19 at 08:45

MongoDB find by Id in nested array

3 Answers3