Currently, I’m using a small child document to reference other collections:

{ name: 'xxx', id: 'xxx'}

.. instead of a manual reference.

So, for a forum post, I might have this:

{
    title: 'Some title',
    creator: { name: 'jgauffin', id: ObjectId(123445455) },
    posts: [...]
}

The reason is that I do not have to do any lookups in other collections each time I fetch a document, and names hardly change.

But since I’m new to this, are there any established design patterns for this? Or are you supposed to do $lookup even for a single field in other collections?