Laravelで多言語サイトのベースを作る。言語切替え＆Cookie保存＆後から言語追加可能に

'timezone' => 'UTC',

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

 App::setLocale($locale);

<?php

$supportedLanguages = [
    'en' => 'english',
    'ja' => '日本語',
]; 

return [
    'supported' => $supportedLanguages,
    'default' => array_key_first($supportedLanguages),
];

php artisan lang:publish

<?php
return [
    'welcome' => 'Welcome to our first multilingual site!',
];

<?php
return [
    'welcome' => '初めての多言語サイトへようこそ！',
];

<?php

use App\Http\Controllers\WebController;
use Illuminate\Support\Facades\Route;

Route::get('/', function () {
    //ミドルウェアでなんとかしてくれる
});

// 各言語の下層（例： /ja 以下など実質の公開サイト）
Route::group(['prefix' => '{locale}', 'where' => ['locale' => '[a-z]{2}']], function () {
    Route::get('/', [WebController::class, 'index'])->name('web.index');
    Route::post('/set-language', [WebController::class, 'setLanguage'])->name('web.change-language');
});

php artisan make:middleware SetLocale

<?php

namespace App\Http\Middleware;

use Closure;
use App;

class SetLocale
{
    public function handle($request, Closure $next)
    {
        $supportedLanguages = array_keys(config('languages.supported'));
        $defaultLanguage = config('languages.default');
        $routeLocale = $request->route('locale');

        if ($routeLocale && !in_array($routeLocale, $supportedLanguages)) {
             // サポートされていない言語コード
            abort(404);
        }

        $cookieLocale = $request->cookie('app_locale');
        if ($cookieLocale && !in_array($cookieLocale, $supportedLanguages)) {
            // 不正なクッキーは無視
            $cookieLocale = '';
        }

        // topページへのリクエスト
        if ($request->path() == '/') {
            if ($cookieLocale) {
                $locale = $cookieLocale;
            } else {
                $locale = $this->getDefaultLanguage($supportedLanguages, $defaultLanguage);
            }
            return redirect('/' . $locale);
        }

        $locale = $routeLocale ?: $this->getDefaultLanguage($supportedLanguages, $defaultLanguage);
        App::setLocale($locale);

        return $next($request);
    }

    private function getDefaultLanguage($supportedLanguages, $defaultLanguage)
    {
        $language = request()->getPreferredLanguage($supportedLanguages);
        if (!$language) {
            $language = $defaultLanguage;
        }
        return $language;
    }
}

// 中略
protected $middlewareGroups = [
        'web' => [
            \App\Http\Middleware\EncryptCookies::class,
            \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,
            \Illuminate\Session\Middleware\StartSession::class,
            \Illuminate\View\Middleware\ShareErrorsFromSession::class,
            \App\Http\Middleware\VerifyCsrfToken::class,
            \Illuminate\Routing\Middleware\SubstituteBindings::class,
            \App\Http\Middleware\SetLocale::class,
        ],
// 中略

make:controller WebController

<?php

namespace App\Http\Controllers;

use Illuminate\Http\Request;
use Illuminate\View\View;

class WebController extends Controller
{
    // 言語トップ
    public function index(Request $request): View
    {
        return view('index', [
            'locale' => app()->getLocale(),
            'cookieLocale' => $request->cookie('app_locale'),
            'preferredLocale' => request()->getPreferredLanguage(),
        ]);
    }

    // 言語セット
    public function setLanguage(Request $request, $locale)
    {
        // テストのため短めに30秒とする
        $cookie = cookie('app_locale', $locale, 30);

        // 直前のページ（実際はバリデーションして使う）
        $previousUrl = $request->input('currentPath', '/');
        $updatedUrl = preg_replace('/\/[a-z]{2}(\/|$)/', "/{$locale}", $previousUrl);

        return redirect($updatedUrl)->withCookie($cookie);       
    }
}

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

<x-language-selector />

<br>
appLocale:
{{ $locale }}
<br>
cookieLocale:
{{ $cookieLocale }}
<br>
preferredLocale
{{ $preferredLocale }}

php artisan make:component LanguageSelector

<?php

namespace App\View\Components;

use Closure;
use Illuminate\Contracts\View\View;
use Illuminate\View\Component;

class LanguageSelector extends Component
{
    public $languages;
    public $currentLocale;

    /**
     * Create a new component instance.
     */
    public function __construct()
    {
        $this->languages = config('languages.supported');
        $this->currentLocale = app()->getLocale();
    }

    /**
     * Get the view / contents that represent the component.
     */
    public function render(): View|Closure|string
    {
        return view('components.language-selector');
    }
}

<form id="js-languageForm" method="POST" action="">
    @csrf
    <input type="hidden" name="currentPath" value="/{{ request()->path() }}">
    <select name="language" onchange="updateActionAndSubmit(this);">
        @foreach ($languages as $code => $name)
            <option value="{{ $code }}" {{ $currentLocale == $code ? 'selected' : '' }}>
                {{ $name }}
            </option>
        @endforeach
    </select>
</form>

<script>
    function updateActionAndSubmit(select) {
        var selectedLanguage = select.value;
        var form = document.getElementById('js-languageForm');
        form.action = '/' + selectedLanguage + '/set-language';
        form.submit();
    }
</script>