[v4] is there currently a way to programmatically generate the .d.json.ts files from createMessagesDeclaration?

[stefanprobst]

it would be cool if i could generate message .d.json.ts files in a postinstall/prepare lifecycle, so that linter and typechecker know about them without running the nextjs app first.

[amannn]

The declaration file is currently generated anytime the Next.js config is read, and optionally runs in a continuous fashion if in dev mode. Therefore anytime you invoke a command from the next CLI, the declaration file will be generated first (e.g. next lint, next build—which includes lint by default).

Does that help?

[stefanprobst]

hmm, i am not running eslint and tsc via the next cli, so i think i'd prefer a way to generate the dts files which can be called in a postinstall script:

// package.json
{
  "scripts": {
    "postinstall": "tsx ./scripts/generate-the-i18n-dts-files.ts"
  }
}

[amannn]

I see. The generation of the declaration file is really workaround for the time being, I hope to get rid of it at some point when microsoft/TypeScript#32063 becomes a thing. Therefore I'd like to not introduce more public API than absolutely necessary for now.

As a side note, for ESLint this shouldn't make a difference, the declaration file is only relevant to tsc which runs as part of next build by default. Also, it merely introduces stricter types than what you have out-of-the-box, so your lint should pass in any case. But if you check types during next build, you can get stricter validation.

[amannn]

It seems like it was a good idea to wait a bit here, the newly added next typegen can now be used to also create the messages declaration!

Related: I've added a minor cleanup in relation to this feature in #1992.

[stefanprobst]

see #1832 (comment)