Add MongoDB client promise for usage in Auth providers

[hdodov]

I'm using Payload 3.0.0-beta.84 with Auth.js and its MongoDB adapter to persist the sessions in the database.

The problem is that I have to provide the connected MongoDB client (or a promise for it) to Auth.js and Payload doesn't provide it. This means I have to do nasty workarounds with exporting promises:

src/payload.config.ts

import { buildConfig } from "payload";
import { resolvePromise } from "./db";

export default buildConfig({
  // ...
  onInit(payload) {
    resolvePromise(payload.db.connection.getClient());
  },
});

src/auth.ts

import { MongoDBAdapter } from "@auth/mongodb-adapter";
import NextAuth from "next-auth";
import Okta from "next-auth/providers/okta";
import { clientPromise } from "./db";

export const { handlers, signIn, signOut, auth } = NextAuth({
  adapter: MongoDBAdapter(clientPromise),
  providers: [Okta],
});

src/db.ts

import type payload from 'payload'

type MongoClient = ReturnType<typeof payload.db.connection.getClient>

export let clientPromise: Promise<MongoClient>
export let resolvePromise: (value: MongoClient) => void

if (process.env.NODE_ENV === 'development') {
  // In development mode, use a global variable so that the value
  // is preserved across module reloads caused by HMR (Hot Module Replacement).
  let globalWithMongo = global as typeof globalThis & {
    _mongoClient?: typeof clientPromise
  }
  if (!globalWithMongo._mongoClient) {
    globalWithMongo._mongoClient = new Promise<MongoClient>((resolve) => (resolvePromise = resolve))
  }
  clientPromise = globalWithMongo._mongoClient
} else {
  // In production mode, it's best to not use a global variable.
  clientPromise = new Promise<MongoClient>((resolve) => (resolvePromise = resolve))
}

What I tried

If I try this straight away:

export const { handlers, signIn, signOut, auth } = NextAuth({
  adapter: MongoDBAdapter(payload.db.connection.getClient()),
  // ...
})

…I get the following error:

TypeError: Cannot read properties of undefined (reading 'connection')

…so the db object is not available yet.

Ideal solution

If Payload has a promise that resolves when the MongoDB client is available, I could simply do:

export const { handlers, signIn, signOut, auth } = NextAuth({
  adapter: MongoDBAdapter(payload.dbClientPromise),
  // ...
})

[DanRibbens]

We have this for the postres and sqlite adapters. You could make a PR to add it to mongodb.

It is named initializing and we have resolveInitializing and rejectInitializing. So in your case you'd have payload.db.initializing,

In the db type we have:
initializing: Promise<void>
resolveInitializing: () => void, and
rejectInitializing: () => void

The adapters set it up in index.ts with:

    let resolveInitializing
    let rejectInitializing

    const initializing = new Promise<void>((res, rej) => {
      resolveInitializing = res
      rejectInitializing = rej
    })

In connect, we call it:
if (typeof this.resolveInitializing === 'function') this.resolveInitializing() andon error connecting: if (typeof this.rejectInitializing === 'function') this.rejectInitializing()

and destroy resets it:

  this.initializing = new Promise((res, rej) => {
    this.resolveInitializing = res
    this.rejectInitializing = rej
  })

[hdodov]

Thanks for the speedy reaction! I've implemented the feature on branch feat/mongodb-client-promise in my fork.

However, that still doesn't quite fix my issue. If you look at my initial comment, payload.db is undefined, so payload.db.initializing is undefined as well.

I have a reproduction branch too. Here's how to see the issue:

1. Clone the repo and check out the branch

2. Run pnpm dev admin-root

3. Open http://localhost:3000/my-route

4. You'll see the error as described here hdodov@194ae1a:

   TypeError: Cannot read properties of undefined (reading 'initializing')

---

I think it could work if we have payload.dbInitializing because the actual payload object itself isn't undefined. What do you think?