diff --git a/public/_static/blogs/next-intl/outside-components.png b/public/_static/blogs/next-intl/outside-components.png new file mode 100644 index 0000000..4fd989f Binary files /dev/null and b/public/_static/blogs/next-intl/outside-components.png differ diff --git a/public/_static/blogs/next-intl/type-safety.mp4 b/public/_static/blogs/next-intl/type-safety.mp4 new file mode 100644 index 0000000..5d5b97f Binary files /dev/null and b/public/_static/blogs/next-intl/type-safety.mp4 differ diff --git a/src/content/next-intl-i18n.mdx b/src/content/next-intl-i18n.mdx new file mode 100644 index 0000000..a5ea9cb --- /dev/null +++ b/src/content/next-intl-i18n.mdx @@ -0,0 +1,563 @@ +--- +title: "Typesafe Internationalization (i18n) in Next.js with next-intl" +summary: "Comprehensive guide to internationalize your Next.js app with next-intl, typesafety for translation strings, split translations into multiple files and translate outside React components." +type: Blog +publishedAt: 2024-09-30 +draft: false +--- + +## Goals + +Before diving deep lets list down goal of this article: +- Integrate next-intl in Next.js app (App router) +- Use next-intl outside of React components +- Split translations strings into multiple files +- Introduce typesafety in translations +- Use next-intl with server components + +## Pre-requisites + +Make sure you have bootstraped a Next.js app (v 13.x+) with Typescript. + +Also make sure you've installed `next-intl`: + +```bash +npm install next-intl +``` + + +## Setting up translation strings + +Before starting lets make sure that we have our locales ready. For this example we will use English (en) and Nepali (ne) locales. + +Create a folder named `messages` in the root of your project, crate two folders `en` and `ne` inside the `messages` folder. + +Normally, next-intl docs recommends you to create single file for each translations, but creating multiple files will help us to manage translations for different components and features. +and the translations won't be too large in a single file. + +Inside each locale folder create a json file with the name of the locale. + +In our case we will create two files called `auth.json` and `users.json` inside the `en` and `es` folders. + +- `messages/en/auth.json` +- `messages/en/users.json` +- `messages/ne/auth.json` +- `messages/ne/users.json` + +The sole purpose of these files is to store the translations for the auth and users modules. + +```json +// messages/en/auth.json +{ + "auth": { + "login": "Login", + "register": "Register" + } +} +``` + +```json +// messages/en/users.json +{ + "users": { + "title": "Users", + "form" : { + "name": "Name", + "email": "Email" + } + } +} +``` + +```json +// messages/ne/auth.json +{ + "auth": { + "login": "लगइन गर्नुहोस्", + "register": "दर्ता गर्नुहोस्" + } +} + +``` + +```json +// messages/ne/users.json +{ + "users": { + "title": "प्रयोगकर्ताहरू", + "form": { + "name": "नाम", + "email": "इमेल" + } + } +} +``` + + +> 🧠 Pro tip : Use [https://translate.i18next.com/](https://translate.i18next.com/) to translate your messages to different languages. + + +## Configuring routing for next-intl + +I highly recommend you to checkout the default [guide provided by next-intl](https://next-intl-docs.vercel.app/docs/getting-started/app-router/with-i18n-routing) before proceeding further. + +Here's overall structure of the project: + +```bash +├── messages +│ ├── en +│ │ ├── auth.json +│ │ └── users.json +│ ├── ne +│ │ ├── auth.json +│ │ └── users.json +├── next.config.js +├── global.d.ts +└── src + ├── i18n + │ ├── routing.ts + │ ├── routing.ts + │ └── types.ts + ├── middleware.ts + └── app + └── [locale] + ├── components + │ └── LocaleSwitcher.tsx + ├── layout.tsx + └── page.tsx +``` + + +Configure the plugin in your `next.config.js` file. + +```js +// next.config.js +const createNextIntlPlugin = require('next-intl/plugin'); + +const withNextIntl = createNextIntlPlugin(); + +/** @type {import('next').NextConfig} */ +const nextConfig = {}; + +module.exports = withNextIntl(nextConfig); +``` + + +#### Configuring routing + +create a folder called `i18n` inside `src` where we put all the configuration related to next-intl and export from there. + +First define the routing in `src/i18n/routing.ts` file. + +```ts +import { createSharedPathnamesNavigation } from "next-intl/navigation"; +import { defineRouting } from "next-intl/routing"; + +export const routing = defineRouting({ + locales: ["en", "ne"], + defaultLocale: "en", + pathnames: {}, +}); + +export type Pathnames = keyof typeof routing.pathnames; +export type Locale = (typeof routing.locales)[number]; + +export const { Link, permanentRedirect, redirect, usePathname, useRouter } = + createSharedPathnamesNavigation(routing); +``` + +The above sample is fairly simple and we have copied it from [docs itself](https://next-intl-docs.vercel.app/docs/getting-started/app-router/with-i18n-routing#i18n-routing). + + +#### Middleware setup + +Setup middleware to redirect to the correct locale based on the user's preferences. + +```ts +// middleware.ts +import createMiddleware from "next-intl/middleware"; +import { routing } from "./i18n/routing"; + +export default createMiddleware(routing); + +export const config = { + matcher: [ + // Enable a redirect to a matching locale at the root + "/", + + // Set a cookie to remember the previous locale for + // all requests that have a locale prefix + "/(ne|en)/:path*", + + // Enable redirects that add missing locales + // (e.g. `/pathnames` -> `/en/pathnames`) + "/((?!_next|_vercel|.*\\..*).*)", + ], +}; + +``` + +#### Setup Server components configuration +Create request-scoped configuration object to provide messages and other options based on user locale's to Server components. + +```ts +// src/i18n/request.ts (make sure path is same as next-intl reads this path by default) +import { notFound } from "next/navigation"; +import { getRequestConfig } from "next-intl/server"; +import { routing } from "./routing"; + +export default getRequestConfig(async ({ locale }) => { + // Validate that the incoming `locale` parameter is valid + if (!routing.locales.includes(locale as any)) notFound(); + + return { + messages: { + ...(await import(`../../messages/${locale}/users.json`)), + ...(await import(`../../messages/${locale}/auth.json`)), + }, + }; +}); + +``` + + +#### Layout and Pages setup + +Setup layout with provider to provide translations to the components. + +```tsx +// src/app/[locale]/layout.tsx + +import {NextIntlClientProvider} from 'next-intl'; +import {getMessages} from 'next-intl/server'; + +export default async function LocaleLayout({ + children, + params: {locale} +}: { + children: React.ReactNode; + params: {locale: string}; +}) { + // Providing all messages to the client + // side is the easiest way to get started + const messages = await getMessages(); + + return ( + + + + {children} + + + + ); +} +``` + +Create a page component to render the layout. + +```tsx +"use client"; + +import {useTranslations} from 'next-intl'; + +export default function HomePage() { + const i18n = useTranslations(); + + return ( +
+

{i18n('users.title')}

+

{i18n('auth.login')}

+
+ ); +} +``` + +#### Locale switcher component +Also somewhere in the app makre sure to put the `LocaleSwitcher` component. +Here's brief code on how to create `LocaleSwitcher` component. I've used [shadcn ui](https://ui.shadcn.com/) for components. + +```tsx +// src/app/[locale]/components/LocaleSwitcher.tsx +"use client"; + +import { Button } from "@/components/ui/button"; +import { + DropdownMenu, + DropdownMenuContent, + DropdownMenuRadioGroup, + DropdownMenuRadioItem, + DropdownMenuTrigger, +} from "@components/ui/dropdown-menu"; +import { ChevronDown, Languages } from "lucide-react"; +import React, { useTransition } from "react"; +import { useSearchParams } from "next/navigation"; +import { Locale, usePathname, useRouter } from "../i18n/routing"; +import { ChevronDown, Languages } from "lucide-react"; + +const locales = [ + { value: "en", label: "English" }, + { value: "ne", label: "Nepali" }, +]; + +export function LocaleSwitcherDropdown() { + const router = useRouter(); + const [isPending, startTransition] = useTransition(); + const pathname = usePathname(); + const searchParams = useSearchParams(); + const locale = useLocale(); + + + function onChange(value: string) { + const nextLocale = value as Locale; + + startTransition(() => { + router.replace(`${pathname}?${new URLSearchParams(searchParams)}`, { + locale: nextLocale, + }); + router.refresh(); + }); + } + + return ( + + + + + + + {locales.map((val) => ( + + {val.label} + + ))} + + + + ); +} +``` + + +## Typesafety in translations + +By default next-intl doesn't provide typesafety in translations, that means there is high chance of typo errors in translations. + +eg : `i18n('users.abc')` instead of `i18n('users.title')` or we might access the translations which are not defined in the translations file. + +To overcome this we can create a global type definition file `global.d.ts` and define the types for translations. + + +In root of the project create a file called `global.d.ts` and define the types for translations. + +```ts +// global.d.ts + +type UsersMessages = typeof import("./messages/en/users.json"); +type AuthMessages = typeof import("./messages/en/auth.json"); + +// Importing other language files .. + +// Create a new type by combining all message types +type Messages = UsersMessages & AuthMessages; + +declare interface IntlMessages extends Messages {} +``` + + +Only catch is that you need to have same translation structure for both `en` and `ne` locales since we take `en` as base for typesafety. + + +Now if you try to access the translations which are not defined in the translations file, you will get typesafety error. + + + + + +Also if you are using server components and using `getTranslations` method, its equally typesafe. + + +```ts +import {getTranslations} from 'next-intl/server'; + +export default async function HomePage() { + const i18n = await getTranslations(); + + return ( +
+

{i18n('users.title')}

+

{i18n('auth.login')}

+
+ ) +} +``` + + +### Using translations outside of React components + +Till now we have seen how to use translations inside React components, but what if we want to use translations outside of React components. + +Infact there's blog on [How (not) to use translations outside of React components](https://next-intl-docs.vercel.app/blog/translations-outside-of-react-components) which recommends +not to use translations outside of React components. + +But sometimes things like array of objects, or in some utility functions we might need translations. Putting this inside the components +might not be a good idea since the components might be too larger. + +In that case it will be better if we can pass the translations instance as a parameter to the function and the function can use the translations. + + +Before that let's create a utility type which will help to access the translations outside of React components in type-safe way. + +Create a file called `types.ts` inside the `i18n` folder. + +```ts +// src/i18n/types.ts + +import { useTranslations } from "next-intl"; + +import { ReactElement, ReactNode } from "react"; +import { + Formats, + MessageKeys, + NamespaceKeys, + NestedKeyOf, + NestedValueOf, + RichTranslationValues, + TranslationValues, +} from "next-intl"; + +export interface TFunction< + NestedKey extends NamespaceKeys< + IntlMessages, + NestedKeyOf + > = never, +> { + < + TargetKey extends MessageKeys< + NestedValueOf< + { + "!": IntlMessages; + }, + [NestedKey] extends [never] ? "!" : `!.${NestedKey}` + >, + NestedKeyOf< + NestedValueOf< + { + "!": IntlMessages; + }, + [NestedKey] extends [never] ? "!" : `!.${NestedKey}` + > + > + >, + >( + key: TargetKey, + values?: TranslationValues, + formats?: Partial, + ): string; + rich< + TargetKey extends MessageKeys< + NestedValueOf< + { + "!": IntlMessages; + }, + [NestedKey] extends [never] ? "!" : `!.${NestedKey}` + >, + NestedKeyOf< + NestedValueOf< + { + "!": IntlMessages; + }, + [NestedKey] extends [never] ? "!" : `!.${NestedKey}` + > + > + >, + >( + key: TargetKey, + values?: RichTranslationValues, + formats?: Partial, + ): string | ReactElement | ReactNode; + raw< + TargetKey extends MessageKeys< + NestedValueOf< + { + "!": IntlMessages; + }, + [NestedKey] extends [never] ? "!" : `!.${NestedKey}` + >, + NestedKeyOf< + NestedValueOf< + { + "!": IntlMessages; + }, + [NestedKey] extends [never] ? "!" : `!.${NestedKey}` + > + > + >, + >(key: TargetKey): any; +} + +``` + +> 😵‍💫 The above type is bit confusing, you can just copy and paste 🤪, Thanks to [fitimbytyqi](https://github.com/amannn/next-intl/issues/500#issuecomment-2358249892) for providing snippet + + +Now let's access the instance of translations outside of React components. + +```tsx +// src/[locale]/page.tsx + +"use client"; +import { useTranslations } from "next-intl"; +import { TFunction } from "../i18n/types"; + +const getNavItems = (i18n: TFunction) => [ + { label: i18n("auth.login"), href: "/login" }, + { label: i18n("auth.register"), href: "/signup" }, +]; + +export default function HomePage() { + const i18n = useTranslations(); + + return ( +
+

{i18n("users.email")}

+
    + {getNavItems(i18n).map((item) => ( +
  • + {item.label} +
  • + ))} +
+
+ ); +} + +``` + + +We pass the translations instance to the `getNavItems` function and the function can use the translations. The i18n instance is type-safe and we can't access the translations which are not defined in the translations file. + + Translations outside of React components + + +## Wrapping up + +Next-intl is a great library to internationalize your Next.js app. It supports most seamless way of applying internationalization to Next.js app with support for server components. +Although there are some limitations like translations outside of React components, low typesafety in translations, but we can overcome these limitations by using some workarounds as mentioned in this article. + +If you have any questions or feedback, feel free to reach out to me on [X.com](https://x.com/adarsha_ach) / [Linkedin](https://www.linkedin.com/in/adarshaacharya/) or comment below.