mongoose find from nested array of objects

Question

hey I am quite new to mongoose and can't get my head around search.

models

User->resumes[]->employments[]

UserSchema

{
    resumes: [ResumeSchema],
    ...
}

ResumeSchema

{
    employments: [EmploymentSchema],
    ...
}

EmploymentSchema

{
    jobTitle: {
        type: String,
        required: [true, "Job title is required."]
    },
    ...
}

Background

User has to enter job title and needs suggestions from the existing data of the already present resumes and their employment's job title

I have tried the following code.

let q = req.query.q; // Software
User.find({ "resumes.employments.jobTitle": new RegExp(req.query.q, 'ig') }, {
    "resumes.employments.$": 1
}, (err, docs) => {
    res.json(docs);
})

Output

[
    {
        _id: '...',
        resumes:[
            {
                employments: [
                    {
                      jobTitle: 'Software Developer',
                      ...
                    },
                    ...
                ]
            },
            ...
        ]
    },
    ...
]

Expected OutPut

["Software Developer", "Software Engineer", "Software Manager"]

Problem 1:) The Data returned is too much as I only need jobTitle

2:) All employments are being returned whereas the query matched one of them

3:) Is there any better way to do it ? via index or via $search ? I did not find much of information in mongoose documentation to create search index (and I also don't really know how to create a compound index to make it work)

I know there might be a lot of answers but none of them helped or I was not able to make them work ... I am really new to mongodb I have been working with relational databases via SQL or through ORM so my mongodb concepts and knowledge is limited.

So please let me know if there is a better solution to do it. or something to make the current one working.

J.F. · Accepted Answer · 2021-09-07 21:49:04Z

2

You can use one of the aggregation query below to get this result:

[
  {
    "jobTitle": [
      "Software Engineer",
      "Software Manager",
      "Software Developer"
    ]
  }
]

Query is:

First using $unwind twice to deconstructs the arrays and get the values.
Then $match to filter by values you want using $regex.
Then $group to get all values together (using _id: null and $addToSet to no add duplicates).
And finally $project to shown only the field you want.

User.aggregate({
  "$unwind": "$resumes"
},
{
  "$unwind": "$resumes.employments"
},
{
  "$match": {
    "resumes.employments.jobTitle": {
      "$regex": "software",
      "$options": "i"
    }
  }
},
{
  "$group": {
    "_id": null,
    "jobTitle": {
      "$addToSet": "$resumes.employments.jobTitle"
    }
  }
},
{
  "$project": {
    "_id": 0
  }
})

Example here

Also another option is using $filter into $project stage:

Is similar as before but using $filter instead of $unwind twice.

User.aggregate({
  "$unwind": "$resumes"
},
{
  "$project": {
    "jobs": {
      "$filter": {
        "input": "$resumes.employments",
        "as": "e",
        "cond": {
          "$regexMatch": {
            "input": "$$e.jobTitle",
            "regex": "Software",
            "options": "i"
          }
        }
      }
    }
  }
},
{
  "$unwind": "$jobs"
},
{
  "$group": {
    "_id": null,
    "jobTitle": {
      "$addToSet": "$jobs.jobTitle"
    }
  }
},
{
  "$project": {
    "_id": 0
  }
})

Example here

edited Sep 7, 2021 at 21:49

answered Sep 7, 2021 at 21:42

J.F.

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2 Comments

anees Over a year ago

Got it working .. thank you.. just one thing .. The mongoose version I am using was expecting the aggregation pipelines in array of objects not as parameters ...

anees Over a year ago

and thank you very much for detailed explanation ... that really makes a lot of sense now ..

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