gatsby-pingbot/lib/dbConnect.ts

import { connect } from 'mongoose'

interface CachedMongo {
  conn: typeof import('mongoose')
  promise: Promise<typeof import('mongoose')>
}

const { MONGODB_URI } = process.env

let cached: CachedMongo = global.mongo

if (!cached) {
  cached = global.mongo = {
    conn: null,
    promise: null
  }
}

export default async function dbConnect() {
  if (cached.conn)
    return cached.conn

  if (!cached.promise)
    cached.promise = connect(MONGODB_URI)

  cached.conn = await cached.promise

  return cached.conn
}