"You are trying to create client-side redirections to paths that do not exist" to folders without trailing slash

Have you read the Contributing Guidelines on issues?

• I have read the Contributing Guidelines on issues.

Prerequisites

• I’m using the latest version of Docusaurus.
• I have tried the npm run clear or yarn clear command.
• I have tried rm -rf node_modules yarn.lock package-lock.json and re-installing packages.
• I have tried creating a repro with https://new.docusaurus.io.
• I have read the console error message carefully (if applicable).

Description

For paths to folders without a trailing slash, hosts will typically 302 redirect to the path with the slash

e.g. https://docs.sheetjs.com/docs/getting-started redirects to https://docs.sheetjs.com/docs/getting-started/

@docusaurus/plugin-client-redirects does not seem to be aware of this behavior for folders that have subfolders.

This redirect works

        { from: '/docs/installation', to: '/docs/getting-started/' }, // works

This redirect elicits the error mentioned in the title:

        { from: '/docs/installation', to: '/docs/getting-started' }, // elicits error

The fact that it works for leaf folders that only have index.html suggests this is a bug in the redirect scanner:

        { from: '/docs/example', to: '/docs/getting-started/example' }, // this works, even though `example` is a folder

Reproducible demo

https://github.com/SheetJS/docs.sheetjs.com

Steps to reproduce

git clone --depth=1 https://github.com/SheetJS/docs.sheetjs.com
cd docs.sheetjs.com/docz
npm i
npm run build ## note: this should work
sed -I '' "s#started/'#started'#g" docusaurus.config.js
npm run build ## this will fail with the aforementioned error

If the sed command fails, the edit is in docusaurus.config.js:

       redirects: [
         { from: '/docs/example', to: '/docs/getting-started/example' },
-        { from: '/docs/installation', to: '/docs/getting-started/' },
+        { from: '/docs/installation', to: '/docs/getting-started' },
       ]
     }]

Expected behavior

It should create the redirect

Actual behavior

[ERROR] Error: You are trying to create client-side redirections to paths that do not exist:

The path in question is not listed in the valid paths

Your environment

No response

Self-service

• I’d be willing to fix this bug myself.

[SheetJSDev]

In a structure like:

/docs/index.md
/docs/foo/index.md
/docs/foo/bar.md

When trailingSlash is undefined, the routesPaths key exposed to in the postBuild props is:

[
  "/docs/",
  "/docs/foo/",
  "/docs/foo/bar"
]

Those paths are used in the validation.

One way to resolve the issue without disrupting other plugins is to add both slash variants to the validation.

https://github.com/facebook/docusaurus/blob/4b5a47ba37ffdfbcf46e23790ff0cfe6c4745e14/packages/docusaurus-plugin-client-redirects/src/collectRedirects.ts#L81

const allowedToPaths = pluginContext.relativeRoutesPaths.flatMap(x => { const y = x.replace(/\/+$/, ""); return [y, y + "/"] });

[slorber]

Happy to review your PR

@slorber The site started from the default config (npx create-docusaurus@latest). The default site does not include the trailingSlash setting. If it is strongly encouraged to use a default setting, should the default site include some trailingSlash setting?

We recommend an explicit trailing slash, but only for Github Pages users, not all users.

I wouldn’t recommend GitHub pages in the first place, Vercel/Netlify are much better alternatives and you don’t always need to use the trailingSlash setting with those.