Code generator

code-generator.ts

import { Db } from 'mongodb'

// Increments the `count` field of the `codes` collection and returns it.
// This function is "thread safety".
//
// It's important to update and find the document at the same time.
// Otherwise a "race condition" may arise.
const newCode = async (db: Db, name: string) => {
  const { value: { count } } = await db.collection('codes').findOneAndUpdate({ name }, { $inc: { count: 1 } }, {
    upsert: true,
    returnDocument: 'after'
  })

  return count
}