Laravel i18n : คู่มือการรองรับหลายภาษาและโลคัลไลเซชันอย่างครบถ้วน

composer create-project laravel/laravel my-app
cd my-app

# Laravel includes i18n out of the box
# No extra packages needed for basic usage

// config/app.php
return [
    'locale' => 'en',            // Default locale
    'fallback_locale' => 'en',   // Fallback when key is missing
    'faker_locale' => 'en_US',

    // Available locales (for your language switcher)
    'available_locales' => ['en', 'de', 'ja', 'es', 'fr', 'pt-BR'],
];

// app/Http/Middleware/SetLocale.php
namespace App\Http\Middleware;

use Closure;
use Illuminate\Http\Request;

class SetLocale
{
    public function handle(Request $request, Closure $next)
    {
        $locale = $request->segment(1); // e.g. /de/about

        if (in_array($locale, config('app.available_locales'))) {
            app()->setLocale($locale);
        }

        return $next($request);
    }
}

// lang/en/messages.php
return [
    'welcome' => 'Welcome to our application',
    'greeting' => 'Hello, :name!',
    'nav' => [
        'home' => 'Home',
        'about' => 'About',
        'settings' => 'Settings',
    ],
];

// lang/de/messages.php
return [
    'welcome' => 'Willkommen in unserer Anwendung',
    'greeting' => 'Hallo, :name!',
    'nav' => [
        'home' => 'Startseite',
        'about' => 'Über uns',
        'settings' => 'Einstellungen',
    ],
];

// lang/en.json
{
    "Welcome back!": "Welcome back!",
    "You have :count new notifications": "You have :count new notifications",
    "Copyright :year :company": "Copyright :year :company"
}

// lang/de.json
{
    "Welcome back!": "Willkommen zurück!",
    "You have :count new notifications": "Sie haben :count neue Benachrichtigungen",
    "Copyright :year :company": "Copyright :year :company"
}

{{-- Simple translation --}}
<h1>{{ __('messages.welcome') }}</h1>

{{-- With variables --}}
<p>{{ __('messages.greeting', ['name' => $user->name]) }}</p>

{{-- Using @lang directive --}}
<h2>@lang('messages.nav.home')</h2>

{{-- JSON translations (use the string itself as key) --}}
<p>{{ __('Welcome back!') }}</p>

{{-- Pluralization --}}
{{ trans_choice('{0} No items|{1} One item|[2,*] :count items', $count) }}

{{-- Inside Blade components --}}
<x-button>{{ __('messages.nav.settings') }}</x-button>

// Install locale chain package
composer require i18n-agent/laravel-locale-chain

// config/locale-chain.php
return [
    'chains' => [
        'pt-BR' => ['pt-BR', 'pt', 'en'],
        'zh-Hant-TW' => ['zh-Hant-TW', 'zh-Hant', 'zh', 'en'],
        'es-419' => ['es-419', 'es', 'en'],
    ],
];

// In AppServiceProvider::boot()
use I18nAgent\LocaleChain\LocaleChainServiceProvider;

// The package automatically deep-merges translations
// across the chain: pt-BR -> pt -> en