lgp-admin-plus/docs/src/en/guide/in-depth/locale.md

# Internationalization

The project has integrated [Vue i18n](https://kazupon.github.io/vue-i18n/), and Chinese and English language packs have been configured.

## IDE Plugin

If you are using vscode as your development tool, it is recommended to install the [i18n Ally](https://marketplace.visualstudio.com/items?itemName=Lokalise.i18n-ally) plugin. It can help you manage internationalization copy more conveniently. After installing this plugin, you can see the corresponding language content in your code in real-time:

![](/public/guide/locale.png)

## Configure Default Language

You just need to override the default preferences. In the corresponding application, find the `src/preferences.ts` file and modify the value of `locale`:

```ts {3}
export const overridesPreferences = defineOverridesPreferences({
  app: {
    locale: 'en-US',
  },
});
```

## Dynamic Language Switching

Switching languages consists of two parts:

- Updating preferences
- Loading the corresponding language pack

```ts
import type { SupportedLanguagesType } from '@vben/locales';
import { loadLocaleMessages } from '@vben/locales';
import { updatePreferences } from '@vben/preferences';

async function updateLocale(value: string) {
  // 1. Update preferences
  const locale = value as SupportedLanguagesType;
  updatePreferences({
    app: {
      locale,
    },
  });
  // 2. Load the corresponding language pack
  await loadLocaleMessages(locale);
}

updateLocale('en-US');
```

## Adding Translation Texts

::: warning Attention

- Do not place business translation texts inside `@vben/locales` to better manage business and general translation texts.
- When adding new translation texts and multiple language packs are available, ensure to add the corresponding texts in all language packs.

:::

To add new translation texts, simply find `src/locales/langs/` in the corresponding application and add the texts accordingly, for example:

**src/locales/langs/zh-CN/\*.json**

````ts
```json
{
  "about": {
    "desc": "Vben Admin 是一个现代的管理模版。"
  }
}
````

**src/locales/langs/en-US.ts**

````ts
```json
{
  "about": {
    "desc": "Vben Admin is a modern management template."
  }
}
````

## Using Translation Texts

With `@vben/locales`, you can easily use translation texts:

### In Code

```vue
<script setup lang="ts">
import { computed } from 'vue';
import { $t } from '@vben/locales';

const items = computed(() => [{ title: $t('about.desc') }]);
</script>
<template>
  <div>{{ $t('about.desc') }}</div>
  <template v-for="item in items.value">
    <div>{{ item.title }}</div>
  </template>
</template>
```

## Adding a New Language Pack

If you need to add a new language pack, follow these steps:

- Add the corresponding language pack file in the `packages/locales/langs` directory, for example, `zh-TW.json`, and translate the respective texts.
- In the corresponding application, locate the `src/locales/langs` file and add the new language pack `zh-TW.json`.
- Add the corresponding language in `packages/constants/src/core.ts`:

  ```ts
  export interface LanguageOption {
    label: string;
    value: 'en-US' | 'zh-CN'; // [!code --]
    value: 'en-US' | 'zh-CN' | 'zh-TW'; // [!code ++]
  }
  export const SUPPORT_LANGUAGES: LanguageOption[] = [
    {
      label: '简体中文',
      value: 'zh-CN',
    },
    {
      label: 'English',
      value: 'en-US',
    },
    {
      label: '繁体中文', // [!code ++]
      value: 'zh-TW', // [!code ++]
    },
  ];
  ```

- In `packages/locales/typing.ts`, add a new TypeScript type:

  ```ts
  export type SupportedLanguagesType = 'en-US' | 'zh-CN'; // [!code --]
  export type SupportedLanguagesType = 'en-US' | 'zh-CN' | 'zh-TW'; // [!code ++]
  ```

At this point, you can use the newly added language pack in the project.

## Interface Language Switching Function

If you want to disable the language switching display button on the interface, in the corresponding application, find the `src/preferences.ts` file and modify the value of `locale` accordingly:

```ts {3}
export const overridesPreferences = defineOverridesPreferences({
  widget: {
    languageToggle: false,
  },
});
```

## Remote Loading of Language Packs

::: tip Tip

When making interface requests through the project's built-in `request` tool, the default request header will include [Accept-Language](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Accept-Language), allowing the server to dynamically internationalize data based on the request header.

:::

Each application has an independent language pack that can override the general language configuration. You can remotely load the corresponding language pack by finding the `src/locales/index.ts` file in the corresponding application and modifying the `loadMessages` method accordingly:

```ts {3-4}
async function loadMessages(lang: SupportedLanguagesType) {
  const [appLocaleMessages] = await Promise.all([
    // Modify here to load data via a remote interface
    localesMap[lang](),
    loadThirdPartyMessage(lang),
  ]);
  return appLocaleMessages.default;
}
```

## Third-Party Language Packs

Different applications may use third-party component libraries or plugins with varying internationalization methods, so they need to be handled differently. If you need to introduce a third-party language pack, you can find the `src/locales/index.ts` file in the corresponding application and modify the `loadThirdPartyMessage` method accordingly:

```ts
/**
 * Load the dayjs language pack
 * @param lang
 */
async function loadDayjsLocale(lang: SupportedLanguagesType) {
  let locale;
  switch (lang) {
    case 'zh-CN': {
      locale = await import('dayjs/locale/zh-cn');
      break;
    }
    case 'en-US': {
      locale = await import('dayjs/locale/en');
      break;
    }
    // Default to using English
    default: {
      locale = await import('dayjs/locale/en');
    }
  }
  if (locale) {
    dayjs.locale(locale);
  } else {
    console.error(`Failed to load dayjs locale for ${lang}`);
  }
}
```

## Removing Internationalization

Firstly, it is not recommended to remove internationalization, as it is a good development practice. However, if you really need to remove it, you can directly use Chinese copy and then retain the project's built-in language pack, which will not affect the overall development experience. The steps to remove internationalization are as follows:

- Hide the language switching button on the interface, see: [Interface Language Switching Function](#interface-language-switching-function)
- Modify the default language, see: [Configure Default Language](#configure-default-language)
- Disable `vue-i18n` warning prompts, in the `src/locales/index.ts` file, modify `missingWarn` to `false`:

  ```ts
  async function setupI18n(app: App, options: LocaleSetupOptions = {}) {
    await coreSetup(app, {
      defaultLocale: preferences.app.locale,
      loadMessages,
      missingWarn: !import.meta.env.PROD, // [!code --]
      missingWarn: false, // [!code ++]
      ...options,
    });
  }
  ```