How to use a different language in a subtree of a React app?

[kkeri]

I have a localized React app, and I want a subtree of the app to always use English. But the subtree uses some localized components, so I need a way to display them in English regardless of the global settting.

I couldn't find any documentation about this topic. What I tried is essentially this:

• I created a custom I18n object and loaded only English messages.
• I wrapped my subtree in an I18nProvider and passed my custom I18n object.

In spite of this the subtree keeps using the global language setting.

// For use with exclusively English parts of the application.
const engI18n = setupI18n({ locale: 'en', messages: enMessages })
 
function MyEnglishSubtree {
  return (
    <I18nProvider i18n={engI18n}>
      <MyPage />
    </I18nProvider>
  )
}

function MyPage(...) {
  return (
    <AppPage title={t`My Page`}> // Page title is _not_ displayed in English
      ...
    </AppPage>
  )
}

But to my surprise, if I add a local variable i18n to the MyPage component that refers to engI18n, page title is displayed in English.

// For use in exclusively English parts of the application.
export const engI18n = setupI18n({ locale: 'en', messages: enMessages })
 
function MyPage(...) {
  const i18n = engI18n
  return (
    <AppPage title={t`My Page`}> // Page title is displayed in English
      ...
    </AppPage>
  )
}

How to do it properly, without hacks?

[timofei-iatsenko]

The t macro refers to a global i18n object. To achieve your case you need to use few instances of it, and you actually did. What really should be changed it's just a syntax

// For use with exclusively English parts of the application.
const engI18n = setupI18n({ locale: 'en', messages: enMessages })

function MyEnglishSubtree {
  return (
    <I18nProvider i18n={engI18n}>
      <MyPage />
    </I18nProvider>
  )
}

function MyPage(...) {
  const {i18n} = useLingui()
  return (
    <AppPage title={t(i18n)`My Page`}>
      ...
    </AppPage>
  )
}

Here is a doc for t macro https://lingui.dev/ref/macro#t

[kkeri]

@thekip Thank you, your answer helped me move forward.