How to use middleware for multi-language support in Laravel

Laravel is a widely used PHP framework that provides many convenient features and tools, including middleware that supports multiple languages. In this article, we will detail how to use middleware to implement Laravel's multi-language support and provide some specific code examples.

1. Configure language package

First, we need to configure Laravel's language package so that it can support multiple languages. In Laravel, language packages are usually placed in the resources/lang directory, where each language has a corresponding subdirectory. For example, if we want to support English and French, we need to create two subdirectories, en and fr, in the resources/lang directory.

Then, in each subdirectory, we need to create a messages.php file that contains all the strings we want to translate. For example, create the messages.php file in the en directory as follows:

return [
    'welcome' => 'Welcome to my website!',
    'about' => 'About us',
    'contact' => 'Contact us',
];

Next, create the messages.php file in the fr directory as follows:

return [
    'welcome' => 'Bienvenue sur mon site web!',
    'about' => 'À propos de nous',
    'contact' => 'Contactez-nous',
];

In this way, we have configured the language package . Next, we need to write middleware to implement multi-language support.

2. Create middleware

In Laravel, we can use middleware to handle requests. Therefore, we can create a middleware that checks the user's language settings and loads the appropriate language pack based on their settings. The following is a simple middleware example:

<?php

namespace AppHttpMiddleware;

use Closure;
use IlluminateHttpRequest;

class SetLanguage
{
    public function handle(Request $request, Closure $next)
    {
        // 检查请求中是否设置了语言参数
        $language = $request->input('lang', 'en');

        // 检查语言包是否存在
        if (!in_array($language, ['en', 'fr'])) {
            abort(400, 'Invalid language');
        }

        // 设置当前语言
        app()->setLocale($language);

        // 继续处理请求
        return $next($request);
    }
}

This middleware will read the lang parameter in the request and set the current language based on its value. If there is no lang parameter in the request, it will default to English. If an invalid language is specified in the request, it will return an HTTP 400 error.

We can register this middleware in the app/Http/Kernel.php file as follows:

protected $middlewareGroups = [
    'web' => [
        AppHttpMiddlewareSetLanguage::class,
        // ...
    ],
    // ...
];

In this way, each request will go through this middleware and set the current language .

3. Using multilingual strings

Now that we have configured the language pack and middleware, we can use multilingual strings in our code. Laravel provides a translation function trans(), which can select the corresponding string according to the current language. For example, we can use it in the view:

<h1 id="trans-messages-welcome">{{ trans('messages.welcome') }}</h1>

In this example, the trans() function will select the corresponding "welcome" string based on the current language. If the current language is English, it will return "Welcome" to my website!", if in French it will return "Bienvenue sur mon site web!".

In addition to views, we can also use the trans() function in controllers, form validators, email templates, etc. anywhere.

Summary

In this article, we introduced how to use Laravel's middleware to achieve multi-language support and provided some specific code examples. By using this approach we can easily add multilingual functionality to our application.

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