MongoDB connection dependency injection

mongo-db.ts

import { json } from 'body-parser'
import * as express from 'express'
import { Db, MongoClient } from 'mongodb'

const uri = `mongodb://username:password@random-mongo-server:port/db-name`

const connection: MongoClient = new MongoClient(uri, { useNewUrlParser: true })

const db = {
  connect: async () => {
    const _connection = await connection.connect()
    return _connection.db()
  },
  disconnect: () => connection.close()
}

const createRandomRouter = (db: Db) => {
  const randomRouter = express.Router()

  randomRouter.get('/', (req, res) => {
    db.collection('random-collection')
      .find()
      .toArray((_, data) => res.json(data))
  })

  return randomRouter
}

const routes = (app, db) => {
  app.use('/random', createRandomRouter(db))
  return app
}

const port = 1337

const app = express()
app.use(json())

db.connect().then((db: Db) => {
  routes(app, db).listen(port, () => console.log(`Listening to port: ${port}`))
})