feat: add property bundle.onlyLocales (#2478)

docs/content/3.options/7.bundle.md

@@ -58,3 +58,16 @@ If you use this option, you need to enable the `compilation.jit` option.
 ::alert{type="warning"}
 If you enable this option, **you should check resources in your application are pre-compiled with nuxt i18n module**. If you will be loading resources dynamically from the back-end via the API, enabling this option does not work because there is no message compiler.
 ::
+
+### `onlyLocales`
+
+- type: `string | string[]`
+- default: `undefined`
+
+Specify the locales codes that need to be included, the rest will be removed.
+
+It can be useful if you have one code base (e.g. [Nuxt Layers](https://nuxt.com/docs/getting-started/layers)) for several similar projects using different languages.
+
+::alert{type="warning"}
+The value of this **option will not be merged with other Nuxt Layers**. This option should only be specified in the final project config.
+::

specs/exclude_locales.spec.ts

@@ -0,0 +1,28 @@
+import { test, expect } from 'vitest'
+import { fileURLToPath } from 'node:url'
+import { setup, url, createPage } from './utils'
+import { getText } from './helper'
+
+await setup({
+  rootDir: fileURLToPath(new URL(`./fixtures/locale_codes`, import.meta.url)),
+  browser: true,
+  // overrides
+  nuxtConfig: {
+    i18n: {
+      bundle: {
+        onlyLocales: 'en'
+      }
+    }
+  }
+})
+
+test('leave only English locale', async () => {
+  const home = url('/')
+  const page = await createPage()
+  await page.goto(home)
+
+  const locales = await page.locator('li')
+
+  expect(await locales.count()).toEqual(1)
+  expect(await getText(page, 'li')).toMatch('en')
+})

specs/fixtures/locale_codes/app.vue

@@ -0,0 +1,12 @@
+<script setup lang="ts">
+import { useI18n } from '#i18n'
+const { locales } = useI18n()
+</script>
+
+<template>
+  <ul>
+    <li v-for="locale in locales" :key="locale.code">
+      {{ locale.code }}
+    </li>
+  </ul>
+</template>

specs/fixtures/locale_codes/i18n.config.ts

@@ -0,0 +1,4 @@
+export default {
+  legacy: false,
+  fallbackLocale: 'en'
+}

specs/fixtures/locale_codes/layers/i18n-layer/i18n.config.ts

@@ -0,0 +1,9 @@
+export default defineI18nConfig(() => {
+  return {
+    messages: {
+      ja: {
+        layerText: 'これはマージされたロケールキーです'
+      }
+    }
+  }
+})

specs/fixtures/locale_codes/layers/i18n-layer/nuxt.config.ts

@@ -0,0 +1,28 @@
+// import type { NuxtApp } from 'nuxt/dist/app/index'
+
+// https://nuxt.com/docs/guide/directory-structure/nuxt.config
+export default defineNuxtConfig({
+  modules: ['@nuxtjs/i18n'],
+  i18n: {
+    locales: [
+      {
+        code: 'en',
+        iso: 'en-US',
+        name: 'English'
+      },
+      {
+        code: 'fr',
+        iso: 'fr-FR',
+        name: 'Francais'
+      },
+      {
+        code: 'nl',
+        iso: 'nl-NL',
+        name: 'Nederlands'
+      }
+    ],
+    bundle: {
+      onlyLocales: ['en', 'fr']
+    }
+  }
+})

specs/fixtures/locale_codes/modules/ExtendI18n.ts

@@ -0,0 +1,33 @@
+import { defineNuxtModule } from '@nuxt/kit'
+
+export default defineNuxtModule({
+  async setup(options, nuxt) {
+    nuxt.hook('i18n:registerModule', register => {
+      register({
+        langDir: './lang',
+        locales: [
+          {
+            code: 'en',
+            iso: 'en-US',
+            name: 'English'
+          },
+          {
+            code: 'fr',
+            iso: 'fr-FR',
+            name: 'Francais'
+          },
+          {
+            code: 'nl',
+            iso: 'nl-NL',
+            name: 'Nederlands'
+          },
+          {
+            code: 'ja',
+            iso: 'ja-JP',
+            name: 'Japanese'
+          }
+        ]
+      })
+    })
+  }
+})

specs/fixtures/locale_codes/nuxt.config.ts

@@ -0,0 +1,35 @@
+// https://nuxt.com/docs/guide/directory-structure/nuxt.config
+export default defineNuxtConfig({
+  modules: ['./modules/ExtendI18n'],
+
+  extends: './layers/i18n-layer',
+
+  vite: {
+    build: {
+      minify: false
+    }
+  },
+
+  experimental: {
+    reactivityTransform: true
+  },
+
+  i18n: {
+    baseUrl: 'http://localhost:3000',
+    locales: [
+      {
+        code: 'en',
+        iso: 'en',
+        name: 'English'
+      },
+      {
+        code: 'fr',
+        iso: 'fr-FR',
+        name: 'Français'
+      }
+    ],
+    defaultLocale: 'en',
+    skipSettingLocaleOnNavigate: true,
+    detectBrowserLanguage: false
+  }
+})

specs/fixtures/locale_codes/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "nuxt3-test-locale-codes",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "build": "nuxi build",
+    "dev": "nuxi dev",
+    "generate": "nuxi generate",
+    "preview": "nuxi preview"
+  },
+  "devDependencies": {
+    "@nuxtjs/i18n": "latest",
+    "nuxt": "latest"
+  }
+}

src/bundler.ts

@@ -44,6 +44,7 @@ export async function extendBundler(nuxt: Nuxt, nuxtOptions: Required<NuxtI18nOp
       runtimeOnly: nuxtOptions.bundle.runtimeOnly,
       compositionOnly: nuxtOptions.bundle.compositionOnly,
       jitCompilation: nuxtOptions.compilation.jit,
+      onlyLocales: nuxtOptions.bundle.onlyLocales,
       dropMessageCompiler: nuxtOptions.compilation.jit ? nuxtOptions.bundle.dropMessageCompiler : false,
       strictMessage: nuxtOptions.compilation.strictMessage,
       escapeHtml: nuxtOptions.compilation.escapeHtml
@@ -88,6 +89,7 @@ export async function extendBundler(nuxt: Nuxt, nuxtOptions: Required<NuxtI18nOp
     runtimeOnly: nuxtOptions.bundle.runtimeOnly,
     compositionOnly: nuxtOptions.bundle.compositionOnly,
     fullInstall: nuxtOptions.bundle.fullInstall,
+    onlyLocales: nuxtOptions.bundle.onlyLocales,
     jitCompilation: nuxtOptions.compilation.jit,
     dropMessageCompiler: nuxtOptions.compilation.jit ? nuxtOptions.bundle.dropMessageCompiler : false,
     strictMessage: nuxtOptions.compilation.strictMessage,

src/module.ts

@@ -32,7 +32,8 @@ import {
   getPackageManagerType,
   mergeI18nModules,
   applyOptionOverrides,
-  getLocaleFiles
+  getLocaleFiles,
+  filterLocales
 } from './utils'
 import { distDir, runtimeDir, pkgModulesDir } from './dirs'
 import { applyLayerOptions, checkLayerOptions, resolveLayerVueI18nConfigInfo } from './layers'
@@ -127,6 +128,7 @@ export default defineNuxtModule<NuxtI18nOptions>({
 
     applyLayerOptions(options, nuxt)
     await mergeI18nModules(options, nuxt)
+    filterLocales(options, nuxt)
 
     /**
      * setup runtime config

src/types.ts

@@ -74,7 +74,10 @@ export interface ExperimentalFeatures {
 }
 
 export interface BundleOptions
-  extends Pick<PluginOptions, 'compositionOnly' | 'runtimeOnly' | 'fullInstall' | 'dropMessageCompiler'> {}
+  extends Pick<
+    PluginOptions,
+    'compositionOnly' | 'runtimeOnly' | 'fullInstall' | 'dropMessageCompiler' | 'onlyLocales'
+  > {}
 
 export interface CustomBlocksOptions extends Pick<PluginOptions, 'defaultSFCLang' | 'globalSFCScope'> {}
 

src/utils.ts

@@ -47,6 +47,28 @@ export function formatMessage(message: string) {
   return `[${NUXT_I18N_MODULE_ID}]: ${message}`
 }
 
+export function castArray<T>(value: T | T[]): T[] {
+  return Array.isArray(value) ? value : [value]
+}
+
+export function normalizeIncludingLocales(locales?: string | string[]) {
+  return (castArray(locales) ?? []).filter(isString)
+}
+
+export function filterLocales(options: Required<NuxtI18nOptions>, nuxt: Nuxt) {
+  const project = getLayerI18n(nuxt.options._layers[0])
+  const includingLocales = normalizeIncludingLocales(project?.bundle?.onlyLocales)
+
+  if (!includingLocales.length) {
+    return
+  }
+
+  options.locales = options.locales.filter(locale => {
+    const code = isString(locale) ? locale : locale.code
+    return includingLocales.includes(code)
+  }) as string[] | LocaleObject[]
+}
+
 export function getNormalizedLocales(locales: NuxtI18nOptions['locales']): LocaleObject[] {
   locales = locales || []
   const normalized: LocaleObject[] = []