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Recipe: Migrating from i18n-js to react-i18next (#177)
* Add initial content for recipe * Point to i18n file within Ignite * Rewrite based on new PRs * Adding more content * Add manage dependencies section and adjust steps * Add last step to swap locale with language method * More improvements * Update title correctly * PR feedback and improvements * Add example and other fixes * Add pickSupportedLocale to step 3
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title: Migrating from i18n-js to react-i18next | ||
description: How to migrate from i18n-js to react-i18next | ||
tags: | ||
- i18n | ||
last_update: | ||
author: Felipe Peña | ||
publish_date: 2024-09-25 | ||
--- | ||
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# Migrating from i18n-js to react-i18next within an Ignite project | ||
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## Overview | ||
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In this guide, we will be going through the steps required to migrate your Ignite generated project from using `i18n-js` to the `react-i18next` library. It is meant specifically for projects generated with version 9 and below. | ||
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`react-i18next` will be included in Ignite's version 10. If you're using an earlier version, this guide provides the necessary steps to successfully complete the migration. | ||
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Finally, the steps outlined in this guide, are based on the changes outlined in the following two PRs: | ||
* [Swap out i18n-js for react-18next](https://github.com/infinitered/ignite/pull/2770) | ||
* [Fix language switching and update date-fns to v4](https://github.com/infinitered/ignite/pull/2788) | ||
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## Step 1: Manage dependencies | ||
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Remove the `i18n-js` package and its types: | ||
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```bash | ||
yarn remove i18n-js @types/i18n-js@types/i18n-js | ||
``` | ||
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Add the two new dependencies: | ||
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```bash | ||
yarn add react-i18next i18next | ||
``` | ||
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## Step 2: Set up initialization logic in app.tsx | ||
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To ensure that `react-i18next` finishes initializing before your app proceeds, we recommend adding state and logic to the `app.tsx` entry file: | ||
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1. Create a state variable, `isI18nInitialized`, to track initialization status. | ||
2. Use the `useEffect` hook to set the state when initialization completes. | ||
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```js | ||
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// error-line | ||
import "./i18n" | ||
// success-line | ||
import { initI18n } from "./i18n" | ||
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// ...extra file logic | ||
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// success-line-start | ||
const [isI18nInitialized, setIsI18nInitialized] = useState(false); | ||
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useEffect(() => { | ||
initI18n().then(() => setIsI18nInitialized(true)); | ||
}, []); | ||
// success-line-end | ||
``` | ||
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Additionally, consider including the new state variable in the rendering condition for the app. | ||
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```js | ||
// error-line-start | ||
if (!rehydrated || !isNavigationStateRestored || (!areFontsLoaded && !fontLoadError)) { | ||
// error-line-end | ||
// success-line-start | ||
if (!rehydrated || !isNavigationStateRestored || !isI18nInitialized || (!areFontsLoaded && !fontLoadError)) { | ||
// success-line-end | ||
return null | ||
} | ||
``` | ||
This ensures that your app will wait until `react-i18next` is fully initialized before continuing, preventing any issues with missing translations. | ||
## Step 3: Remove i18n-js from project | ||
In `app/i18n/i18n.ts`, delete the import line for i18n-js. | ||
```js | ||
// error-line | ||
import { I18n } from "i18n-js" | ||
``` | ||
## Step 4: Update the i18n initialization method | ||
Next, update your i18n initialization to use `react-i18next`, which also includes RTL (right-to-left) language support and handles locale selection. In a Ingnite generated project, this is located in `app/i18n/i18n.ts`. | ||
```js | ||
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// success-line-start | ||
import * as i18next from "i18next" | ||
import { initReactI18next } from "react-i18next" | ||
import en from "./en" | ||
import ar from "./ar" | ||
import ko from "./ko" | ||
import es from "./es" | ||
import fr from "./fr" | ||
import ja from "./ja" | ||
import hi from "./hi" | ||
// success-line-end | ||
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// ...extra file logic | ||
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// error-line-start | ||
export const i18n = new I18n( | ||
{ ar, en, "en-US": en, ko, fr, ja, hi }, | ||
{ locale: fallbackLocale, defaultLocale: fallbackLocale, enableFallback: true }, | ||
) | ||
// error-line-end | ||
// success-line-start | ||
const resources = { ar, en, ko, es, fr, ja, hi } | ||
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const pickSupportedLocale: () => Localization.Locale | undefined = () => { | ||
return systemLocales.find((locale) => systemTagMatchesSupportedTags(locale.languageTag)) | ||
} | ||
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const locale = pickSupportedLocale() | ||
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export const initI18n = async () => { | ||
await i18n.use(initReactI18next).init({ | ||
resources, | ||
lng: locale?.languageTag ?? fallbackLocale, | ||
fallbackLng: fallbackLocale, | ||
interpolation: { escapeValue: false }, | ||
}); | ||
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const locale = pickSupportedLocale(); | ||
if (locale?.textDirection === 'rtl') { | ||
I18nManager.allowRTL(true); | ||
isRTL = true; | ||
} else { | ||
I18nManager.allowRTL(false); | ||
isRTL = false; | ||
} | ||
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return i18n; | ||
}; | ||
// success-line-end | ||
``` | ||
This ensures that supported locales are chosen based on the device’s settings, and RTL is correctly applied when necessary. For more on detail on these changes, check the [this PR](https://github.com/infinitered/ignite/pull/2770). | ||
## Step 5: Add intl-pluralrules for react-i18next and JSON v4 | ||
To support pluralization and `react-i18next`'s JSON v4 format, you’ll need to add the `intl-pluralrules` package: | ||
```bash | ||
yarn add intl-pluralrules | ||
``` | ||
Make sure to import this package into your i18n configuration file (`app/i18n/i18n.ts`): | ||
```js | ||
// success-line | ||
import 'intl-pluralrules'; | ||
``` | ||
## Step 6: Update the translate function | ||
The next step is to replace your old translate function with the one provided by `react-i18next`. This is located in `app/i18n/translate.ts`: | ||
```js | ||
// error-line | ||
import { TranslateOptions } from "i18n-js" | ||
// success-line-start | ||
import { TOptions } from "i18next" | ||
import { TxKeyPath } from "./i18n" | ||
// success-line-end | ||
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// error-line-start | ||
export function translate(key: TxKeyPath, options?: TranslateOptions): string { | ||
return i18n.t(key, options) | ||
// error-line-end | ||
// success-line-start | ||
export function translate(key: TxKeyPath, options?: TOptions) { | ||
return i18n.isInitialized ? i18n.t(key, options) : key; | ||
// success-line-end | ||
} | ||
``` | ||
## Step 7: Update translation keys from dots (.) to colons (:) | ||
`react-i18next` uses different types of separators for translation keys. Colons (:) are used for first-level translations within an object, while dots (.) are used for nested translations. As a result, you’ll need to update all translation keys in your app accordingly. For example: | ||
```js | ||
translate("common.ok") | ||
``` | ||
Should be changed to: | ||
```js | ||
translate("common:ok") | ||
``` | ||
### Example | ||
Using Ignite’s boilerplate code, here’s an example of how to replace the separator in `i18next`. We’ll use the `WelcomeScreen` component as a reference: | ||
```js | ||
// error-line-start | ||
useHeader( | ||
{ | ||
rightTx: "common.logOut", | ||
onRightPress: logout, | ||
}, | ||
[logout], | ||
) | ||
// error-line-end | ||
// success-line-start | ||
useHeader( | ||
{ | ||
rightTx: "common:logOut", | ||
onRightPress: logout, | ||
}, | ||
[logout], | ||
) | ||
// success-line-end | ||
``` | ||
Or from the return statement itself: | ||
```tsx | ||
// error-line-start | ||
return ( | ||
<View style={$container}> | ||
<View style={$topContainer}> | ||
<Image style={$welcomeLogo} source={welcomeLogo} resizeMode="contain" /> | ||
<Text | ||
testID="welcome-heading" | ||
style={$welcomeHeading} | ||
tx="welcomeScreen.readyForLaunch" | ||
preset="heading" | ||
/> | ||
<Text tx="welcomeScreen.exciting" preset="subheading" /> | ||
<Image style={$welcomeFace} source={welcomeFace} resizeMode="contain" /> | ||
</View> | ||
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<View style={[$bottomContainer, $bottomContainerInsets]}> | ||
<Text tx="welcomeScreen.postscript" size="md" /> | ||
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<Button | ||
testID="next-screen-button" | ||
preset="reversed" | ||
tx="welcomeScreen.letsGo" | ||
onPress={goNext} | ||
/> | ||
</View> | ||
</View> | ||
) | ||
}) | ||
// error-line-end | ||
// success-line-start | ||
return ( | ||
<View style={$container}> | ||
<View style={$topContainer}> | ||
<Image style={$welcomeLogo} source={welcomeLogo} resizeMode="contain" /> | ||
<Text | ||
testID="welcome-heading" | ||
style={$welcomeHeading} | ||
tx="welcomeScreen:readyForLaunch" | ||
preset="heading" | ||
/> | ||
<Text tx="welcomeScreen:exciting" preset="subheading" /> | ||
<Image style={$welcomeFace} source={welcomeFace} resizeMode="contain" /> | ||
</View> | ||
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<View style={[$bottomContainer, $bottomContainerInsets]}> | ||
<Text tx="welcomeScreen:postscript" size="md" /> | ||
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<Button | ||
testID="next-screen-button" | ||
preset="reversed" | ||
tx="welcomeScreen:letsGo" | ||
onPress={goNext} | ||
/> | ||
</View> | ||
</View> | ||
) | ||
}) | ||
// success-line-end | ||
``` | ||
## Step 8: Update types in i18n.ts | ||
To prevent errors related to the `tx` property and accommodate `i18next`'s use of `:` as the primary separator, we need to update the types in `app/i18n/i18n.ts`. | ||
```js | ||
// error-line-start | ||
type RecursiveKeyOf<TObj extends object> = { | ||
[TKey in keyof TObj & (string | number)]: RecursiveKeyOfHandleValue<TObj[TKey], `${TKey}`> | ||
}[keyof TObj & (string | number)] | ||
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type RecursiveKeyOfInner<TObj extends object> = { | ||
[TKey in keyof TObj & (string | number)]: RecursiveKeyOfHandleValue< | ||
TObj[TKey], | ||
`['${TKey}']` | `.${TKey}` | ||
> | ||
}[keyof TObj & (string | number)] | ||
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type RecursiveKeyOfHandleValue<TValue, Text extends string> = TValue extends any[] | ||
? Text | ||
: TValue extends object | ||
? Text | `${Text}${RecursiveKeyOfInner<TValue>}` | ||
: Text | ||
// error-line-end | ||
// success-line-start | ||
type RecursiveKeyOf<TObj extends object> = { | ||
[TKey in keyof TObj & (string | number)]: RecursiveKeyOfHandleValue<TObj[TKey], `${TKey}`, true> | ||
}[keyof TObj & (string | number)] | ||
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type RecursiveKeyOfInner<TObj extends object> = { | ||
[TKey in keyof TObj & (string | number)]: RecursiveKeyOfHandleValue<TObj[TKey], `${TKey}`, false> | ||
}[keyof TObj & (string | number)] | ||
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type RecursiveKeyOfHandleValue< | ||
TValue, | ||
Text extends string, | ||
IsFirstLevel extends boolean, | ||
> = TValue extends any[] | ||
? Text | ||
: TValue extends object | ||
? IsFirstLevel extends true | ||
? Text | `${Text}:${RecursiveKeyOfInner<TValue>}` | ||
: Text | `${Text}.${RecursiveKeyOfInner<TValue>}` | ||
: Text | ||
// success-line-end | ||
``` | ||
--- | ||
Lastly, update the usage of `i18n`'s `locale` method to `language` instead. For example in `app/utils/formatDate.ts`: | ||
```js | ||
// error-line | ||
import { i18n } from "app/i18n" | ||
// success-line | ||
import i18next from "i18next" | ||
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// ...extra file logic | ||
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// error-line | ||
const locale = i18n.locale.split("-")[0] | ||
// success-line | ||
const locale = i18next.language.split("-")[0] | ||
``` | ||
For detailed code changes, including initialization updates, translation function updates, and testing, refer to the following PRs on the Ignite Github repo: | ||
* [Swap out i18n-js for react-18next](https://github.com/infinitered/ignite/pull/2770) | ||
* [Fix language switching and update date-fns to v4](https://github.com/infinitered/ignite/pull/2788) | ||
By following this guide, you will be able to seamlessly transition your React Native app from `i18n-js` to `react-i18next`, ensuring improved localization features and support for modern internationalization practices. Let us know if you have any questions! |