POST to page handler in draft mode for RSC draft previews

[CaptainN]

Goals

Enable page handlers to answer POST requests when in draft mode.

Non-Goals

We don't want or need this for scenarios outside of draft mode. There may be an argument to add something similar for "dynamic" routes, but that's not my purpose here.

Background

I'm using Payload CMS, and that presents some challenges for their "live preview" mode with RSC. They have a solution, but it's problematic in some ways.

• It relies on a stateful backend. It must save a draft, then load that content on the read side.
• This means, it has to respond to a live change through client side JS, then reload the content, and render.
• This is slow and resource intensive.
• It can produce a race condition where the content is not saved quickly enough, and the refresh completes before the data has made it in to the store.

Solving that with its multiple stages is not super easy.

In Payload, the full content of the update is actually passed through client side. When using client rendering, this is super easy - we can actually just render that, and be done! But there are some production issues with that, which are well documented with the change to RSC (among other issues, the entire payload data block has to be serialized and sent to the client for hydration - and of course, hydration has to happen - bigger data bundle, bigger app bundle, hydration - slow, slow, slower).

BUT - what if we could POST to a page route in draft mode:

• Then we can read the POST payload, and render from that - very similar to how client side live preview works, just using RSC
• We would need no backend data stores, requests remain stateless - no session backing store, no round trip to the CMS database.
• Client refreshes could be throttled, but happen quickly.
• We could do partial rendering in draft mode to make it work.

Proposal

Allow page handlers to answer POST requests. What that might look like. - accessing post body through a helper function, similar to cookies() or headers()) in draft mode - maybe postBody().json() or something similar.

[CaptainN]

Just bumping this - is this possible? To respond to a POST on a page end point (not api or route end point, a page end point)?

[CaptainN]

Oh, I wonder if I can use useFormState for this. hmmmm.

[CaptainN]

Er, I was thinking about this all wrong. No, of course this won't work. The only thing that could possibly work would be some way to POST to a page.tsx handler, with the updated data payload.

[CaptainN]

I could probably use a custom server to achieve this. Seems like overkill. It'd be so much better if I could just POST to a page handler, even if that means everything gets put in dynamic mode - even if it is only available in draftMode.