feat: integrate i18next middleware

.changeset/violet-toes-greet.md

@@ -0,0 +1,5 @@
+---
+'@hono/i18next': major
+---
+
+This middleware adds a translation function (t) for internationalization (i18next) to the context of each request. This function allows you to translate text based on the language preference.

.github/workflows/ci-i18next.yml

@@ -0,0 +1,25 @@
+name: ci-i18next
+on:
+  push:
+    branches: [main]
+    paths:
+      - 'packages/i18next/**'
+  pull_request:
+    branches: ['*']
+    paths:
+      - 'packages/i18next/**'
+
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    defaults:
+      run:
+        working-directory: ./packages/i18next
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-node@v4
+        with:
+          node-version: 20.x
+      - run: yarn install --frozen-lockfile
+      - run: yarn build
+      - run: yarn test

packages/i18next/README.md

@@ -0,0 +1,52 @@
+# i18next middleware for Hono
+
+## Installation
+
+```bash
+bun add @hono/i18next i18next
+# or
+npm install @hono/i18next i18next
+# or
+yarn add @hono/i18next i18next
+```
+
+## Usage
+
+```ts
+import { useI18next, type I18nextMiddlewareOptions } from '@hono/i18next'
+import { Hono } from 'hono'
+
+const app = new Hono()
+
+const options: I18nextMiddlewareOptions = {
+  headerName: 'X-Localization',
+  // if true, it will set the language in the i18next instance
+  setLanguageChanges: false,
+  // i18next options:
+  fallbackLng: 'en',
+  returnNull: false,
+  nsSeparator: '.',
+  interpolation: { escapeValue: false },
+  resources: {
+    en: { translation: { hello: 'Hello!' } },
+    tr: { translation: { hello: 'Merhaba!' } },
+  },
+}
+
+app.use('*', useI18next(options))
+
+app.get('/hello', (c) => {
+  const t = c.get('t')
+  return c.json({ message: t('hello') })
+})
+
+export default app
+```
+
+## Author
+
+Onur Ozkaya <https://github.com/nrzky>
+
+## License
+
+MIT

packages/i18next/jest.config.js

@@ -0,0 +1 @@
+module.exports = require('../../jest.config.js')

packages/i18next/package.json

@@ -0,0 +1,50 @@
+{
+  "name": "@hono/i18next",
+  "version": "1.0.0",
+  "description": "i18next middleware for Hono",
+  "type": "module",
+  "module": "dist/index.js",
+  "types": "dist/index.d.ts",
+  "files": [
+    "dist"
+  ],
+  "scripts": {
+    "test": "vitest --run",
+    "build": "tsup ./src/index.ts --format esm,cjs --dts",
+    "publint": "publint",
+    "release": "yarn build && yarn test && yarn publint && yarn publish"
+  },
+  "exports": {
+    ".": {
+      "import": {
+        "types": "./dist/index.d.ts",
+        "default": "./dist/index.js"
+      },
+      "require": {
+        "types": "./dist/index.d.cts",
+        "default": "./dist/index.cjs"
+      }
+    }
+  },
+  "license": "MIT",
+  "author": "Onur Ozkaya <[email protected]> (https://github.com/nrzky)",
+  "publishConfig": {
+    "registry": "https://registry.npmjs.org",
+    "access": "public"
+  },
+  "repository": {
+    "type": "git",
+    "url": "https://github.com/honojs/middleware.git"
+  },
+  "homepage": "https://github.com/honojs/middleware",
+  "peerDependencies": {
+    "hono": "*",
+    "i18next": "*"
+  },
+  "devDependencies": {
+    "hono": "^4.4.12",
+    "i18next": "^23.11.5",
+    "tsup": "^8.1.0",
+    "vitest": "^1.6.0"
+  }
+}

packages/i18next/src/index.test.ts

@@ -0,0 +1,90 @@
+import { Hono } from 'hono'
+import { HTTPException } from 'hono/http-exception'
+
+import { useI18next } from '../src'
+import type { I18nextMiddlewareOptions } from '../src'
+
+describe('i18next middleware', () => {
+  const en = { hello: 'Hello!', errMsg: 'Opps!' }
+  const tr = { hello: 'Merhaba!', errMsg: 'Hay Aksi!' }
+
+  const fallbackLng = 'en'
+
+  const requestHeaderName = 'X-Localization'
+
+  const options: I18nextMiddlewareOptions = {
+    headerName: requestHeaderName,
+    setLanguageChanges: false,
+    fallbackLng: fallbackLng,
+    returnNull: false,
+    nsSeparator: '.',
+    interpolation: { escapeValue: false },
+    resources: { en: { translation: en }, tr: { translation: tr } },
+  }
+
+  const app = new Hono()
+
+  app.use('*', useI18next(options))
+
+  app.get('/hello', (c) => {
+    const t = c.get('t')
+    return c.json({ message: t('hello') })
+  })
+
+  app.get('/error', (c) => {
+    const t = c.get('t')
+    throw new HTTPException(400, { message: t('errMsg') })
+  })
+
+  app.onError((err, c) => {
+    return c.json({ message: err.message }, err instanceof HTTPException ? err.status : 500)
+  })
+
+  it('Should return hello message in English', async () => {
+    const res = await app.request('http://localhost/hello', {
+      headers: { [requestHeaderName]: 'en' },
+    })
+
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({ message: en.hello })
+  })
+
+  it('Should return hello message in Turkish', async () => {
+    const res = await app.request('http://localhost/hello', {
+      headers: { [requestHeaderName]: 'tr' },
+    })
+
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({ message: tr.hello })
+  })
+
+  it('Should return hello message in fallback language when language not supported', async () => {
+    const res = await app.request('http://localhost/hello', {
+      headers: { [requestHeaderName]: 'fr' },
+    })
+
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({ message: en.hello })
+  })
+
+  it('Should return hello message in fallback language when language is undefined', async () => {
+    const res = await app.request('http://localhost/hello')
+
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(200)
+    expect(await res.json()).toEqual({ message: en.hello })
+  })
+
+  it('Should return error message in English', async () => {
+    const res = await app.request('http://localhost/error', {
+      headers: { [requestHeaderName]: 'en' },
+    })
+
+    expect(res).not.toBeNull()
+    expect(res.status).toBe(400)
+    expect(await res.json()).toEqual({ message: en.errMsg })
+  })
+})

packages/i18next/src/index.ts

@@ -0,0 +1,42 @@
+import { createMiddleware } from 'hono/factory'
+import i18next from 'i18next'
+import type { InitOptions, TFunction } from 'i18next'
+
+declare module 'hono' {
+  interface ContextVariableMap {
+    t: TFunction
+  }
+}
+
+export interface I18nextMiddlewareOptions extends InitOptions {
+  headerName: string
+  setLanguageChanges?: boolean
+}
+
+const useI18next = ({
+  headerName,
+  setLanguageChanges = false,
+  ...initOptions
+}: I18nextMiddlewareOptions) => {
+  if (!i18next.isInitialized) {
+    i18next.init(initOptions)
+  }
+
+  return createMiddleware(async (c, next) => {
+    const language = c.req.header(headerName) || initOptions.lng
+
+    const t = (key: string, options?: object) => {
+      return i18next.t(key, { lng: language, ...options })
+    }
+
+    if (setLanguageChanges) {
+      await i18next.changeLanguage(language)
+    }
+
+    c.set('t', t)
+
+    await next()
+  })
+}
+
+export { i18next, useI18next }

packages/i18next/tsconfig.json

@@ -0,0 +1,8 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "rootDir": "./src",
+    "outDir": "./dist"
+  },
+  "include": ["src/**/*.ts"]
+}

packages/i18next/vitest.config.ts

@@ -0,0 +1,8 @@
+/// <reference types="vitest" />
+import { defineConfig } from 'vitest/config'
+
+export default defineConfig({
+  test: {
+    globals: true,
+  },
+})

yarn.lock

@@ -442,6 +442,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@babel/runtime@npm:^7.23.2":
+  version: 7.24.7
+  resolution: "@babel/runtime@npm:7.24.7"
+  dependencies:
+    regenerator-runtime: "npm:^0.14.0"
+  checksum: b6fa3ec61a53402f3c1d75f4d808f48b35e0dfae0ec8e2bb5c6fc79fb95935da75766e0ca534d0f1c84871f6ae0d2ebdd950727cfadb745a2cdbef13faef5513
+  languageName: node
+  linkType: hard
+
 "@babel/template@npm:^7.22.15, @babel/template@npm:^7.3.3":
   version: 7.22.15
   resolution: "@babel/template@npm:7.22.15"
@@ -2113,6 +2122,20 @@ __metadata:
   languageName: unknown
   linkType: soft
 
+"@hono/i18next@workspace:packages/i18next":
+  version: 0.0.0-use.local
+  resolution: "@hono/i18next@workspace:packages/i18next"
+  dependencies:
+    hono: "npm:^4.4.12"
+    i18next: "npm:^23.11.5"
+    tsup: "npm:^8.1.0"
+    vitest: "npm:^1.6.0"
+  peerDependencies:
+    hono: "*"
+    i18next: "*"
+  languageName: unknown
+  linkType: soft
+
 "@hono/medley-router@workspace:packages/medley-router":
   version: 0.0.0-use.local
   resolution: "@hono/medley-router@workspace:packages/medley-router"
@@ -10116,6 +10139,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"i18next@npm:^23.11.5":
+  version: 23.11.5
+  resolution: "i18next@npm:23.11.5"
+  dependencies:
+    "@babel/runtime": "npm:^7.23.2"
+  checksum: b0bec64250a3e529d4c51e2fc511406a85c5dde3d005d3aabe919551ca31dfc0a8f5490bf6e44649822e895a1fa91a58092d112367669cd11b2eb89e6ba90d1a
+  languageName: node
+  linkType: hard
+
 "iconv-lite@npm:0.4.24, iconv-lite@npm:^0.4.24":
   version: 0.4.24
   resolution: "iconv-lite@npm:0.4.24"