getServerSideProps data urls don't respect assetPrefix

[chrisbrantley]

Bug report

Describe the bug

I have assetPrefix set because we are hosting multiple applications on the same domain and use a proxy to route paths.

assetPrefix = "reports"

The static asset urls are correct. Such as /reports/_next/static/development/pages/_app.js?ts=1587171521639.

However, the data fetching URLs are NOT including the prefix: /_next/data/development/reports/appointments/2020-03-18/2020-04-17.json.

To Reproduce

• Set assetPrefix to anything
• Create a page with getServerSideProps
• use the router (or Link) to go to that page on the client
• Observe in the network request inspector that the data urls do not include the assetPrefix.

Expected behavior

I would expect the assetPrefix to apply to ALL asset urls that start with _next/

[tmayr]

Yep, exactly the same is happening here.

I can confirm that locally works fine, the assetPrefix is present, but on production build it goes away. Even going directly to a getServerSideProps route (not only via router or Link)

Is this the same behavior you're observing @chrisbrantley ?

[chrisbrantley]

@tmayr Yes, that appears to be the behavior I'm seeing. It appears when the client-side request to the data url fails Next.JS falls-back to reloading the entire page to get the server-side-rendered version. So in this case the app still sort of "works" but it's not a good experience and not efficient.

I'm hoping this was just an oversight in implementing these data urls for client-side fetching of server-side props.

[daveskybet]

To add to this i'm seeing the same behaviour with data urls not being prefixed using getStaticProps too for an SSG site, so might be a wider issue than just getServerSideProps

[daveskybet]

Poking about with the code (i'm no expert in the codebase), here seems to be the culprit:

https://github.com/zeit/next.js/blob/canary/packages/next/next-server/lib/router/router.ts#L94

Which seems to add an experimental basePath if exists, rather than the assetPrefix as I would have expected (as gets added to the preload tags for the json files)

A quick addition of the assetPrefix to this line fixes my problem (with an ssg site using getStaticProps), but i'm questioning whether we're misunderstanding the expected behaviour (with the basePath addition)?

[davscro]

@daveskybet have you solved this issue? I am experiencing the same thing

[daveskybet]

@davscro No, I ended up not needing assetPrefix once all the bugs with basePath were solved, basePath sorted all JS paths/Links/Router.push's so assetPrefix wasn't required.

Are you needing assetPrefix without basePath? I suspect the original bug still exists. It looks like there's a discussion on how assetPrefix and data urls should work on the above open PR #13456

[davscro]

Hi @daveskybet,

Yes, you were right. I do not need assetPrefix only basePath is enough and nginx location directive. Now everything works perfectly.

Thanks for the hint. 👍🏼

[Timer]

Please use the new basePath support instead of assetPrefix in Next.js 9.5.1+ for this use case!

[pueyo5]

Please use the new basePath support instead of assetPrefix in Next.js 9.5.1+ for this use case!

@Timer In our case, this is not possible. The basePath is expecting a subfolder, and we want to use a subdomain.
We are using https://cdn.domain.com and for the proposed solution we have to use https://domain.com/cdn.

Can this issue be reopened or do you want me to create a new one?

[yahoohung]

We have tested on our website and basePath is not suitable for our settings : /[locale]/[category]/[[...slug]]

[petewarman]

I need the /_next/data/ urls to be prefixed, but I'm not able to use basePath as that also prefixes my page urls (which is something I don't want). So this fix is actually a major problem for me.

[petewarman]

Started a discussion here to try and find a fix for the problems created by this change #25681

[balazsorban44]

This issue has been automatically locked due to no recent activity. If you are running into a similar issue, please create a new issue with the steps to reproduce. Thank you.