Documentation about Head.rewind

[lcswillems]

Feature request

Is your feature request related to a problem? Please describe.

I see Head.rewind() being used in several examples (e.g. the apollo example) but I don't really understand what it does and can't find documentation about it.

Describe the solution you'd like

If possible, I would like some documentation about it. What happens if I omit it? Could it be possible to have a concrete example?

[timneutkens]

We can get rid of .rewind by now as the latest next/head no longer uses legacy context. I'll open up a PR soon.

[iFallUpHill]

@timneutkens Could you explain what implications this has from a refactoring perspective?
Am I safe to simply not call Head.rewind() if I'm on a 9.1.x release?

[zuqini]

@timneutkens In addition, could you clarify what you mean by legacy context? Is there any other aspects of the code that we need to refactor with this change?

I also see that next/head will be deprecated in the near future. What implications will that have? Thanks!

[dminkovsky]

Very new to Next. My guess based on this thread, the name of the method, and examples I've seen: It's probably got to do with how Head is populated as a side-effect of rendering. In the examples with Head.rewind I've seen, the method is called after rendering that is meant to compute properties for rendering. I'm guessing this undoes changes to Head caused during such renders so it can be populated later.

[jaydenseric]

@iFallUpHill I have done some digging, and it seems that next/head has not used legacy context since next@8.0.0-canary.7, here is the PR that was merged: #6038. Based on this comment above, it can be assumed that it’s safe to stop using Head.rewind() from that version onward.

[timneutkens]

@jaydenseric Head.rewind is currently still needed if you do tree rendering, eg getDataFromTree in Apollo

Would highly recommend not doing tree rendering as it has massive performance implications.

[jaydenseric]

@timneutkens

Head.rewind is currently still needed if you do tree rendering, eg getDataFromTree in Apollo

This is surprising to hear, considering it was deliberately removed from the Next.js Apollo example:

1a50d99#diff-c7ee3d6e815d630e8d7be23ea73b6436L107

Are you sure it is necessary; is your earlier comment and the Apollo example now incorrect?

Would highly recommend not doing tree rendering as it has massive performance implications.

I know all about tree rendering, I've worked with the Apollo one and published before using several different techniques:

• https://github.com/jaydenseric/graphql-react/blob/v6.0.1/src/preload.mjs
• https://github.com/jaydenseric/graphql-react/blob/v9.1.0/src/server/ssr.mjs

Are you able to offer an alternative for server side rendering nested query components?

[timneutkens]

This is surprising to hear, considering it was deliberately removed from the Next.js example:

1a50d99#diff-c7ee3d6e815d630e8d7be23ea73b6436L107

Are you sure it is necessary; is your earlier comment and the Apollo example now incorrect?

Yes I'm pretty sure it's necessary, so yeah the example should be updated.

My comment is still correct, I said "We can get rid of it" haven't had the time to do so because of other priorities.

Are you able to offer an alternative for server side rendering nested query components?

Extracting the data requirements out of the React tree like Relay does and then executing it in getStaticProps/getServerProps (new data fetching methods)

[lfades]

Update: There aren't any examples using Head.rewind anymore and it will be removed soon it's now deprecated.

[timneutkens]

It's not being removed btw, #14091 is backwards compatible

[JustFly1984]

And now it is 2021, and I found one in the legacy code, while updating and refactoring. Just removing it from apollo.tsx

typescript complains that rewind does not exist on Head, which has type ({ children }: { children: ReactNode; }) => Element

[balazsorban44]

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