How to define a route with a specific middleware that runs only on failure in Laravel?

To define a route with a specific middleware that runs only on failure in Laravel, you can follow these steps:

Open the app/Http/Kernel.php file and locate the $routeMiddleware property at the top of the class. Add a new key-value pair for your custom middleware. For example:

protected $routeMiddleware = [
    // Other middleware definitions...
    'custom.middleware' => \App\Http\Middleware\CustomMiddleware::class,
];

Create a new middleware class by running the following command:

php artisan make:middleware CustomMiddleware

This will generate a new file called CustomMiddleware.php inside the app/Http/Middleware directory.

Open the app/Http/Middleware/CustomMiddleware.php file and modify the handle() method. Since you only want the middleware to run on failure, you can use the response() helper function to return a custom response when the request fails. For example:

public function handle($request, Closure $next)
{
    $response = $next($request);

    // Check if the response has a 4xx or 5xx HTTP status code
    if ($response->isClientError() || $response->isServerError()) {
        // Do something on failure
        return response()->json(['message' => 'Request failed'], $response->status());
    }

    return $response;
}

You can modify the logic inside the if block to perform any specific actions you want when the request fails.

Now, open your routes/web.php or routes/api.php file and define the route where you want to apply the middleware. To apply the middleware only on failure, you can use the middleware() method on the route and provide the middleware name as an argument. For example:

Route::get('/example', function () {
    // Your route logic

})->middleware('custom.middleware');

With this setup, the CustomMiddleware will only run if the request fails (returns a 4xx or 5xx HTTP status code).

Remember to replace 'custom.middleware' with an appropriate name for your middleware and modify the logic in the CustomMiddleware class according to your requirements.