Define multiple IntlMessages types for use in monorepo

[jonathanwilke]

Hey there,

I am using next-intl in a monorepo and I am trying to get next-intl running in a lib there that defines my mail templates with react-email. I have two global.d.ts files that define IntlMessages, one in my main project (a Next.js app) and one in the library for the mail templates. The main app imports the mail templates from the library to send the mails. In the editor everything works fine with the types, but if I try to build the app, I get the error that the messages I pass to the createTranslator method are not valid in the mail template library. I suppose this is due to the fact the it takes the IntlMessages type from my main app, which of course does not match the messages of the mail template library.

Is there any way how I can define override the types for a specific instance of the createTranslator method or any other way to fix this?

[amannn]

Hmm, sounds like an issue with how types are used in the respective packages? Can you maybe skip the type check of the email package when building the main app? Sounds like something you might want to do anyway for perf reasons, as long as the email package takes care of checking its types internally?

Maybe something like skipLibCheck does the trick?

[jonathanwilke]

I solved it (temporarilly) now by just putting everything into one language file. This would of course not be a problem if we had scoped translation files.

[amannn]

This sounds mostly like a TypeScript tooling issue, no? I'd say ideally you should have different messages for your email and for your main app package. Each package should be able to define messages and make sure types don't leak into other packages.

[jonathanwilke]

The problem is that the main package imports the other one and at build time this will crash due to type errors

[flipflopsandrice]

I have a similar issue, I'm using TurboRepo.

Let me explain:

package/somename

• Translations package specific type in a translations.d.ts file, exported from the package
• Has components with useTranslations: ✔️ type checking works on build

package/otherone

• Translations package specific type in a translations.d.ts file, exported from the package
• Has components with useTranslations: ✔️ type checking works on build

apps/main:

• Imports Translations types from package/somename and package/otherone in a global.d.ts and extend the IntlMessages interface with a union of the types.
• Has components with useTranslations: ✔️ type checking works on build
• Import components (package/somename) with useTranslations: ⚠️ type checking breaks on build

---

apps/main/global.d.ts

import type { SomenameTranslations } from '@repo/somename/types/translations';
import type { OtheroneTranslations } from '@repo/otherone/types/translations';

declare global {
  interface IntlMessages extends Translations {}
}

export {};

tsc error

main:types: ../../packages/somename/src/components/MyComponent.tsx:22:24 - error TS2345: Argument of type 'string' is not assignable to parameter of type 'never'.
main:types: 
main:types: 22       myPropertyTitle: t('somename.myproperty.title'),