如何在mongo db中进行联合表查询？

Question

I'm quite new with mongodb, in the past I worked with mysql for database queries.

Now I have 2 mongo collections:

1. companies

+--------------+--------------+
|    id        |     name     |
+--------------+--------------+
|     1        |   good name  |
+--------------+--------------+
|     2        |   bad name   |
+--------------+--------------+

2. positions

+--------------+---------------+-------------------+
|      id      |    companyId  |      name         |
+--------------+---------------+-------------------+
|      1       |      1        |     bad position  |
+--------------+---------------+-------------------+
|      2       |      2        |    good position  |
+--------------+---------------+-------------------+

Now I need to allow searching positions by fuzzy matching the name, either company or position name. For example, if I search by name "good", the result should be the 2 positions. Because for the position 1, it's correlated company's name contains "good", and for the position 2, it's own name contains "good".

So how should I arrange the aggregation pipelines to achieve that?

I tried with the following but it doesn't work:

const lookup = {
  from: "companies",
  localField: "companyId",
  foreignField: "_id",
  as: "companies"
};

const match = {
  $or: [
    {
      name: { $regex: companyOrPositionName }
    },
    {
      "companies": { name: { $regex: companyOrPositionName } }
    }
  ]
};

return await position.aggregate([{ $lookup: lookup }, { $match: match }]);

Can anyone help? Thanks in advance!

Answer 1

You can try below aggregation

position.aggregate([
  { "$lookup": {
    "from": "companies",
    "let": { "companyId": "$_id" },
    "pipeline": [
      { "$match": { "$expr": { "$eq": [ "$_id", "$$companyId" ] } } },
      { "$project": { "name": 1 }}
    ],
    "as": "companyName"
  }},
  { "$unwind": "$companyName" },
  { "$match": {
    "$or": [
      { "name": { "$regex": "good" }},
      { "companyName.name": { "$regex": "good" }}
    ]
  }}
])

or either with simple find queries

const companies = await Companies.find({ "name": { "$regex": "good" }})
const ids = companies.map(company => company._id)

position.find({
  "$or": [
    { "companyId": { "$in": ids }},
    { "name": { "$regex": "good" }}
  ]
})