.gitignore

npm-debug.log*
node_modules/

collections.js

const { MongoClient } = require('mongodb')
const { Collection } = require('mongodbext')
const relationsPlugin = require('mongodbext-relations')

exports.connect = async () => {
  const client = await MongoClient.connect('mongodb://localhost:27017')
  const db = client.db('mongodbext-relations-test')

  const coll1 = new Collection(db, 'coll1')

  const coll2 = new Collection(db, 'coll2')
  coll2.addPlugin(relationsPlugin, {
    relations: {
      foreignKey: {
        collection: coll1,
        projection: { _id: 1, foo: 1 }
      }
    }
  })

  return { client, db, coll1, coll2 }
}

index.js

const { EOL } = require('os')
const { connect } = require('./collections')

const test = async (coll1, coll2) => {

  console.log('creating document in coll1')
  const doc1 = await coll1.insertOne({
    foo: 'bar'
  })
  console.log('document created:')
  console.log(doc1)
  console.log(EOL)

  console.log('creating document in coll2')
  const doc2 = await coll2.insertOne({
    foreignKey: doc1
  })
  console.log('document created:')
  console.log(doc2)
  console.log(EOL)

  console.log('updating document in coll1')
  const update1 = await coll1.findOneAndUpdate({
    _id: doc1._id
  }, {
    $set: { foo: 'baz' }
  }, {
    returnOriginal: false
  })
  console.log('document updated:')
  console.log(update1)
  console.log(EOL)

  console.log('reading document in coll2')
  const read1 = await coll2.findOne({
    _id: doc2._id
  })
  console.log('document fetched:')
  console.log(read1)
  console.log(EOL)

  console.log('replacing document in coll1')
  const update2 = await coll1.findOneAndReplace({
    _id: doc1._id
  }, {
    foo: 'foo bar'
  }, {
    returnOriginal: false
  })
  console.log('document updated:')
  console.log(update2)
  console.log(EOL)

  console.log('reading document in coll2')
  const read2 = await coll2.findOne({
    _id: doc2._id
  })
  console.log('document fetched:')
  console.log(read2)
  console.log(EOL)
}

const main = async () => {
  const { client, coll1, coll2 } = await connect()
  try {
    await test(coll1, coll2)
  } catch (err) {
    console.error(err)
  } finally {
    client.close()
  }
}

main()

package-lock.json

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package.json

{
  "author": {
    "name": "Leonid Beschastny",
    "email": "lbeschastny@gmail.com",
    "url": "https://github.com/lbeschastny"
  },
  "dependencies": {
    "mongodb": "^3.1.0-beta4",
    "mongodbext": "^2.2.4",
    "mongodbext-relations": "^1.0.9"
  }
}