[core] Replace getInitialProps with getStaticProps

[mnajdova]

Related to #33196 (comment)

We still need getInitialProps on the non-page files, like _document.js, _app.js etc.

[mui-bot]

No bundle size changes

Generated by 🚫 dangerJS against 52caa28

[Janpot]

A lot of these pages are almost duplicates, I wonder if they can be deduplicated using getStaticPaths and have them generated in the export phase instead of the compilation phase. I wonder whether it would speed up the build since less pages will have to be compiled.

[eps1lon]

I couldn't make this work in the past for all locales. So I would recommend also running export for all locales.

[Janpot]

Yep, using require.context wouldn't be possible in that scenario. It'd need to be replaced with regular filesystem access. Was just mentioning getStaticPaths as it seemed to be the obvious choice for implementing this. Not having tried this, I'm probably overlooking some more potential blockers.

[eps1lon]

I tried it multiple times but never took the time writing down why. It all came down to vervel considering our use case exotic and not helping with guidance etc. It might work now and I would definitely recommend doing it long term. Just be sure to test how master would be deployed not just branches. And test /api and other routes separately.

[oliviertassinari]

I couldn't make this work in the past for all locales. So I would recommend also running export for all locales.

@mnajdova The point of Sebastian is confirmed. This PR broke the SEO structure when it comes to the translations. For example, the page https://mui.com/material-ui/api/table-pagination/ says:

<link rel="alternate" href="https://mui.com/zh/material-ui/api/table-pagination/" hrefLang="zh"/>

But this page is a 404 https://mui.com/zh/material-ui/api/table-pagination/. Chinese users will directly get a 404.

The Google Search console started to raise flags about it (how I landed here). I could find a bit of documentation about it on Next.js's side: vercel/next.js#15315 (comment).

---

What I would propose is to:

1. Fix the regression. Revert this PR (trading a deprecation for a working SEO structure sounds like a good deal). A quick win. The sooner, the better.
2. Have a look at https://nextjs.org/docs/basic-features/data-fetching/get-static-paths as suggested by Jan. It seems that we could get a nice speed up, same for the blog pages.

Otherwise:

1. Fix the regression. The sooner, the better.
   a. Add 301 for all the URLs that are now 404
   b. Remove the alternate hrefLang
   c. Remove the automatic redirection to these missing URL
2. Do point 2. of the proposal above.

[mnajdova]

I don't really have bandwidth to look into this more. I can revert the PR and delegate to someone else on the team to handle.

[oliviertassinari]

delegate to someone else on the team to handle

@mnajdova Ok, sounds great. It will likely be for either:

1. once we need to upgrade Next.js
2. or once we move forward with the implementation of https://mui-org.notion.site/Docs-localization-what-s-next-3f370280b58f446fbb5559dfc08fe03e (considering we are heading for no translations in production). In this effort, we would need to change SEO structure too.