Conflicting rewrites #2 - Incorrect paths in Preview Mode (1.18.0-alpha.16)

New issue per maintainer admonishments. This is continued from https://github.com/serverless-nextjs/serverless-next.js/issues/696, same setup as there (@dphang).

Describe the bug

When using top-level rewrite (per past issues – see rewrites / repo below), upon visiting a route in preview mode, the incorrect URL is passed to getStaticProps (via params). Issue goes away if rewrites are removed, or if not in preview mode.

Actual behavior

URL slug passed in params to getStaticProps is incorrect.

Expected behavior

URL slug passed in params to getStaticProps is correct.

Steps to reproduce

• Deploy my example
• Visit this URL: /api/preview?secret=96ffe7d4-2ad2-4699-b64a-a5f74750962e&slug=/dynamic-1
  • Either check logs, or simply look at the page. The params key incorrectly has part of the rewrite destination in it.
• For added fun, visit the non-rewritten URL for the same page /api/preview?secret=96ffe7d4-2ad2-4699-b64a-a5f74750962e&slug=/content/dynamic-1
  • The app now thinks we’re at /content/content/dynamic-1

Screenshots/Code/Logs

• Reproduction: https://github.com/patricktyndall/sls-next-bug-reproduction
• The rewrite in question:

[{
	source: '/:path*',
	destination: '/content/:path*',
}]

Versions

• OS/Environment: Mac
• @sls-next/serverless-component version: 1.18.0-alpha.16
• Next.js version: 9.5.5

Additional context

~If you visit /content/dynamic-1 not in preview mode, you get a 404. This is also a bug, and is actually a regression added in alpha.16.~

[dphang]

PR for (1): https://github.com/serverless-nextjs/serverless-next.js/pull/719

[patricktyndall]

That’s what I thought too, but from my testing it seemed that Next.js server skips rewrites only for non-dynamic pages and public files

Good catch on this, that’s definitely not intuitive. I would have thought to skip rewrites for anything with a non-dynamic segment. (I wonder if this holds for non-catch-all dynamic segments / rewrites). I guess this is the utility of the “no-op”; that’s not explained well in the next docs.