如何使用nodejs在mongodb中按自定义字段名称（不是_id）查找文档？

Question

I have documents in my mongodb like this

{
        "song_Name": "akon-Breakdown",
        "album_Name": "Akon collection",
        "release_date": "2019-09-11T18:30:00.000Z",
        "description": "akon popular collection",
        "song_image_uri": "http://neptechco.com/assets/akon-breakdown.jpg",
        "song_uri": "https://monal.s3-us-west-2.amazonaws.com/Audio/English/collection/akon-Breakdown.mp3",
        "home_featured": true,
        "_id": "5d7980c1d043b70dfd2dcfc5",
        "song_main_category": "English"
        "__v": 0
    }

Now i am creating an API for finding the song by its song_uri not by its id to check if there is any duplicate song posted.

But i think this is going to be so complex.

If there is any other suggestion to find the song by its song_uri, I would really appreciate the suggestions.

I can do it by finding by id and searching its song_uri in findall API

here is my code how i am trying

let getMusicInfo = (req, res) => {
    const songurl = req.params.songId;
    Music.find({ _id: songurl })
        .exec()
        .then(result => {
            if (result.length > 0) {
                let currentSongURL = result.song_uri;
                Music.find()
                    .exec()
                    .then(docs => {
                        for (let i = 0; i < docs.length; i++) {
                            if (currentSongURL == docs[i].song_uri) {
                                console.log("duplicate")
                            } else {
                                res.status(200).json(result);
                            }
                        }
                    })
                    .catch(err => {
                        res.status(500).json({
                            error: err
                        });
                    })
            }
        })

}

I expect the output to send me duplicate message when the song_uri is already present in any of the document in mogodb.

Answer 1

If you can pass song_uri in query param of GET, as you're not able to make it POST api(ideally url can be passed as string in post request body & be retrieved as req.body.songURL , url in path param of GET is not that feasible) - So if considering query param then you don't need to make two find calls to DB - Once you get the result of .find() if you get more than one record then that song_uri has duplicate records in DB (We're doing exact match for a string, not a partial search & also if this happens often try to have an index on the field & make that text field as text index), Below is sample code - Please try this :

let getMusicInfo = (req, res) => {
    //const songurl = req.params.songId;
    // let's say you get song_uri in songURL
    Music.find({ song_uri: req.query.songURL })
        .exec()
        .then(result => {
            if (result.length > 1) {
                console.log("duplicate")
                res.status(409);
            } else {
                res.status(200).json(result);
            }
        }).catch(err => {
            res.status(500).json({
                error: err
            });
        })

}

else if you don't have song_uri value & only have _id of a song & still need to find duplicates on song_uri (no change in your requirement) then try this, this helps to avoid two DB calls, check on performance of this query :

let getMusicInfo = (req, res) => {
const songID = req.params.songId;
Music.aggregate([{ $project: { song_uri: 1 } },
{ $group: { _id: '$song_uri', doc: { $push: '$$ROOT' } } },
{ $match: { 'doc._id': songID } },
{ $project: { songUrlsCount: { $size: '$doc' } } }])
    .exec()
    .then(result => {
        if (result.length && result.songUrlsCount > 1) {
            console.log("duplicate")
            res.status(409);
        } else {
            res.status(200).json(result);
        }
    }).catch(err => {
        res.status(500).json({
            error: err
        });
    })

}

Or by doing two DB calls(Only change below is instead doing .find() on entire collection & iterating changed to specific thing ie; _id, no change in your requirement) :

let getMusicInfo = (req, res) => {
    const songurl = req.params.songId;
    Music.find({ _id: songurl })
        .exec()
        .then(result => {
            if (result.length > 0) {
                let currentSongURL = result.song_uri;
                Music.find({ song_uri: currentSongURL })
                    .exec()
                    .then(result => {
                        if (result.length > 1) {
                            console.log("duplicate")
                            res.status(409);
                        } else {
                            res.status(200).json(result);
                        }
                    }).catch(err => {
                        res.status(500).json({
                            error: err
                        });
                    })
            }
        }).catch(err => {
            res.status(500).json({
                error: err
            });
        })

}

Please consider this as basic structure, Refactor & think through error scenarios as well..