Change laravel web application default locale dynamically

Understanding the Error

Changing the default locale dynamically in a Laravel web application means updating the language of the application at runtime. Instead of using a fixed language from config/app.php, we switch it based on user selection.

Sometimes developers face issues where the language does not change even after updating the session. This usually happens due to missing middleware registration or incorrect session handling.

Another common confusion is that the locale changes only for one request and resets on refresh. This happens when the session is not properly stored or middleware is not applied in the web group.

Understanding how Laravel handles localization through App::setLocale() and session storage is important. Once configured correctly, the locale will persist across all requests.

Common Causes

Errors while changing locale dynamically usually occur due to the following reasons:

• Middleware not registered in Kernel.php.
• The session is not started, or the session driver is misconfigured.
• Incorrect route parameter handling or mismatch in variable names.

How to Fix the Error

Step: 1 

Create a proper localization middleware and ensure App::setLocale() is called when the session has a locale value. 

<?php

namespace App\Http\Middleware;

use Closure;

use App;

class Localization

{

    /**

* Handle an incoming request.

     *

     * @param  \Illuminate\Http\Request  $request

     * @param  \Closure  $next

     * @return mixed

     */

    public function handle($request, Closure $next)

    {

        if (session()->has('locale')) {

            App::setLocale(session()->get('locale'));

        }

        return $next($request);

    }

}

You can see I have defined localization middleware. Which will check the locale variable in the session, and on each request, it will set the application locale variable.

Step: 2

Register the middleware inside the web middleware group in app/Http/Kernel.php.

/**

* The application's route middleware groups.

     *

     * @var array

     */

    protected $middlewareGroups = [

        'web' => [

            \App\Http\Middleware\EncryptCookies::class,

            \Illuminate\Cookie\Middleware\AddQueuedCookiesToResponse::class,

            \Illuminate\Session\Middleware\StartSession::class,

            // \Illuminate\Session\Middleware\AuthenticateSession::class,

            \Illuminate\View\Middleware\ShareErrorsFromSession::class,

            \App\Http\Middleware\VerifyCsrfToken::class,

            \Illuminate\Routing\Middleware\SubstituteBindings::class,

            \App\Http\Middleware\Localization::class,

        ],

        'api' => [

            'throttle:60,1',

            \Illuminate\Routing\Middleware\SubstituteBindings::class,

        ],

    ];

 \App\Http\Middleware\Localization::class,

Step: 3

Ensure the session is working correctly by checking the .env file (SESSION_DRIVER=file or database).

Route::get('changeLocale/{locale}', function($lang){

    if ($lang == "fr") {

        Session::put('locale', 'fr');

    } else {

        Session::put('locale', 'en');

    }

    return redirect()->back();

});

Here you can see I am setting the locale variable in two languages: English and French. So requests changeLocale/en and changeLocale/fr will set the locale value.

Step: 4

HTML code that will allow us to change language and hit the above GET request.

<li class="eborder-top">
    @if( \Session::get('locale') == "fr"  )
        <a href="{{ url('/changeLocale/en') }}">
            <i class="fa fa-key" aria-hidden="true"></i> English
        </a>
    @else
        <a href="{{ url('/changeLocale/fr') }}">
            <i class="fa fa-key" aria-hidden="true"></i> French
        </a>
    @endif
</li>

Above will check the locale key in the session, and based on that, it will run the route, and after running the route, it will set the session key locale value.

Conclusion

Dynamically changing the Laravel locale is a simple and professional approach to building multilingual applications. By using middleware and session storage, we can control the application language globally.

The key concept is storing the selected language in a session and applying it on every request using middleware. Without middleware, the locale will not persist across pages.

This method is clean, reusable, and scalable for larger projects. It works perfectly for applications that support multiple languages.

Once properly implemented, users can switch languages smoothly without affecting application performance or structure.