`useData` composable

Context: https://github.com/nuxt/framework/issues/7562, https://github.com/nuxt/framework/issues/7562

useState is primarily to preserve initial state between client and server. useAsyncData should be ideally used to store data but sometimes, it is more convenient to use useState and direct async logic to fill it. (usage in nuxt/content document-driven mode).

We can introduce new useData composable that acts almost same as useState but is explicitly marked as page data and can be extracted to the static payloads.

Alternatives:

• useState to always be extracted (like 3.0.0.rc.1) => It introduces network when it is really initial state and same between pages
• useState to track changes => Not sure if possible at all for server but even if is, a custom async logic might initializes it before composable. It also makes implementation more complex internally
• useAsyncData => Seems not fitting for all

[pi0]

(talking in context of full-static)

With #7567, useState will not be cleared on nav

useData is same as useAsyncData only not having an async fetcher and can be replaced for current implementation in nuxt/content of useState. Content modules shall use useData with keys specific to each page for state that is variant to each page. This way it won’t be overridden but cached on CSR nav.

[c-schwan]

@pi0 thx, but if i use the combination of useState and $fetch then i lose the useAsyncData functionality like { server: true | false}, lazy:true.

So i have to duplicate the whole functionality fetching the data and store them