unstable_cache tags based on the request result

[dry tiger]

Hi !

I'm using contentful and Next.js, with the ISR feature. I would like to tag the cache with the different IDs from the contentful entries, so that I can invalidate them easily with the Contentful webhook.

I cannot find a proper way to tag the content with unstable_cache based on the request result. Basically what I want to achieve is what is done here https://nextjs.org/docs/app/api-reference/functions/cacheTag#creating-tags-from-external-data with 'use cache' but with unstable_cache since 'use cache' and cacheTags are not available on the stable release.

Any idea ?

so far the only way I found is to fetch before and leave the async function empty in the unstable_cache but this only helps to tag the page and looses the cache when fetching the RSC.

[rocky idol]

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[barren girder]

I strongly suspect it's not possible, and that's why they've added unstable_cacheTag. I have the same requirements (albeit with Payload CMS and not Contentful, so the terminology I use might not be quite right). Options as I see it:

1. Aggressively revalidate anywhere that could be affected when a record is updated. This might be worth it if the record is actually unlikely to be updated very often …
2. Make all queries flat (depth: 0). E.g. query the page content, then find all the ImageUpload references within, and send a query that gets all of those. I actually did this for another project and it wasn't too bad. It meant revalidation was highly targeted and quick, and every query sent was fast to execute.
3. (I think I might do this until unstable_cacheTag is available) const cachedQuery = (additionalTags: string[]) => unstable_cache(queryFn, [], { ['base-tag', ...additionalTags ] }). Run cachedQuery([]), inspect the result for the additional tags, and run cachedQuery(['additional', 'tags']) and use the response from that instead.