Create language files: Create subdirectories for each language (such as en, es) in the resources/lang directory and add messages.php file, or use JSON file to store translation; 2. Set application language: read the request header Accept-Language through middleware or detect language through URL prefix, set the current language using app()->setLocale(), and register the middleware in Kernel.php; 3. Use translation functions: use __(), trans() or @lang in the view to get the translation content, and it is recommended to use __() that supports fallback; 4. Support parameters and plural: use placeholders such as: name in translation strings, and use trans_choice() to process plural forms such as '{0} No apples|{1} One apple|[2,*] :count apples'; 5. Configure fallback language: Set locale and fallback_locale in config/app.php to ensure fallback to the default language when translation is missing; 6. Optional performance optimization: The production environment can realize translation cache through third-party packages; 7. Front-end integration: Expose translation through the API interface or use framework-specific plug-ins to share language packages; Summary: Laravel internationalization requires structured management of language files, unified use of __() function, dynamically set the language with middleware, and handle parameters, plurals and fallbacks to achieve multilingual support.

Internationalizing a Laravel application allows you to serve content in multiple languages, making your app accessible to a global audience. Laravel provides solid built-in support for localization through language files and helper functions. Here's how to set it up properly.

1. Set Up Language Files

Laravel stores language strings in resources/lang directory. Each language has its own subdirectory (eg, en , es , fr ).

Create language directories and files:

 /resources
  /lang
    /en
      messages.php
    /es
      messages.php

Example: /resources/lang/en/messages.php

 <?php

Return [
    &#39;welcome&#39; => &#39;Welcome to our application&#39;,
    &#39;login&#39; => &#39;Login&#39;,
];

Example: /resources/lang/es/messages.php

 <?php

Return [
    &#39;welcome&#39; => &#39;Bienvenido a nuestra aplicación&#39;,
    &#39;login&#39; => &#39;Iniciar sesión&#39;,
];

You can also use JSON files for single translation strings (eg, resources/lang/es.json ), which Laravel supports natively.

2. Detect and Set the Application Locale

Laravel uses the App::setLocale() method to switch languages. You need to determine the user's preferred language and set it early in the request lifecycle.

Option A: Middleware (Recommended)

Create a middleware to set the locale:

 php artisan make:middleware SetLocale

In app/Http/Middleware/SetLocale.php :

 public function handle($request, \Closure $next)
{
    $locale = $request->header('Accept-Language', 'en');

    // Validate and sanitize locale (eg, 'en', 'es')
    $supportedLocales = ['en', 'es', 'fr'];
    if (! in_array($locale, $supportedLocales)) {
        $locale = 'en'; // fallback
    }

    app()->setLocale($locale);

    return $next($request);
}

Register the middleware in app/Http/Kernel.php under $middleware or a route group.

Option B: URL-Based Locale

You can also pass the locale via the URL:

 Route::get('/{locale}/welcome', function ($locale) {
    app()->setLocale($locale);
    return view('welcome');
});

Or use a route group:

 Route::prefix('{locale}')->middleware('set.locale')->group(function () {
    Route::get('/welcome', [WelcomeController::class, 'index']);
});

Then extract and store the locale in the session or user preferences.

3. Use Translation Functions in Views and Code

Laravel provides several helpers to retrieve translated strings.

Using __() helper:

 <h1>{{ __(&#39;messages.welcome&#39;) }}</h1>
<p>{{ __(&#39;messages.login&#39;) }}</p>

Or with JSON translations:

 <h1>{{ __(&#39;Welcome to our application&#39;) }}</h1>

Using @lang Blade directive:

 @lang('messages.welcome')

Note: @lang does not fall back to other languages ??and is less flexible than __() , so __() is preferred.

Passing Parameters

For dynamic translations:

 // Language file
'hello' => 'Hello, :name',

 {{ __('messages.hello', ['name' => 'John']) }}

4. Pluralization and Choice

Laravel supports pluralization using the trans_choice() function.

Example in language file:

 'apples' => '{0} No apples|{1} One apple|[2,*] :count apples',

Or using placeholders:

 'apples' => 'One apple|:count apples',

Usage:

 {{ trans_choice('messages.apples', 3) }}

This outputs: 3 apples .

5. Fallback and Missing Translations

Laravel falls back to the default locale (defined in config/app.php ) when a translation is missing.

Ensure your config/app.php includes:

 'locale' => 'en',
'fallback_locale' => 'en',

You can log or handle missing translations by extending Laravel's translator, but by default, it returns the key or fallback.

6. Caching Translations (Optional)

In production, you can cache language files for performance:

 php artisan config:cache
php artisan route:cache

While Laravel doesn't provide lang:cache by default, you can use packages like barryvdh/laravel-translation-manager or implement a custom cache layer if needed.

7. JavaScript Integration (Optional)

If your frontend needs translations, consider using packages like spatie/laravel-translatable or inertiajs/inertia with shared props, or expose translations via a secure endpoint:

 Route::get('/translations/{locale}', function ($locale) {
    $translations = translate('messages', [], $locale);
    return response()->json($translations);
});

Or use a package like vue-i18n / laravel-vue-i18n if using Vue.

Summary

To internationalize a Laravel app:

• Store translations in resources/lang/{locale}/
• Use __() or trans() helpers in views and controllers
• Detect language via header, URL, or user settings
• Set locale using middleware
• Support parameters and pluralization
• Handle fallbacks and missing keys

It's not complex, but consistency in structure and planning your locales upfront makes maintenance easier.

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