Cache the getSession result for SvelteKit

[pauldemarco]

Goals

1. Cache the session response for the duration of the request (from hooks -> api endpoint)

Background

Often times, we are awaiting getSession multiple times throughout the single request.

Like in this authorization middleware:

export const authorization: Handle = async ({ event, resolve }) => {
	if (event.url.pathname.startsWith('/api/protected')) {
		const session = await event.locals.getSession();
		if (!session) {
			throw error(401, { message: 'Unauthorized' });
		}
	}
	return resolve(event);
};

Then it happens again in the /api/protected route (since we need access to session data):

export const POST: RequestHandler = async ({ request, locals: { getSession }, fetch }) => {
	const session = await getSession();
	if (!session?.user) {
		throw error(401);
	}

Proposal

Would it be beneficial to cache the result with something like:

  event.locals.getSession = (() => {
    let session;
    return () => session ||= event.locals.getSession().then(r => r.data.session)
  })()