Revalidate on first page load

[gkiely]

Is there a way to trigger a revalidation once on page load?

onMount: true will trigger if I leave the route and re-enter or the component unmounts/remounts, this is not what I am looking for, I want it to trigger the fetch request once on "page" load.
useSWRImmutable will cache indefinitely and not revalidate on page load

[gkiely]

I wrote a custom middleware to do this

import { useRef } from 'react';
import { serialize, useSWRConfig, type Middleware, type SWRHook } from 'swr/_internal';

/**
 * Load data once on page load
 */
export const loadOnce: Middleware = (useSWRNext: SWRHook) => (key, fetcher, config) => {
  const loadedRef = useRef<Set<string>>(new Set());
  const cache = useSWRConfig().cache;
  if (!fetcher) throw new Error('no fetcher provided');

  const k = serialize(key)?.[0];
  const data = cache.get(k)?.data as ReturnType<typeof fetcher>;
  const hasLoaded = data && loadedRef.current.has(k);
  if (cache.get(k)?.data) loadedRef.current.add(k);

  return useSWRNext(key, hasLoaded ? () => data : fetcher, config);
};