PHP exception handling: using Middleware exception handling middleware

PHP exception handling uses Middleware exception handling middleware, which allows exceptions to be handled at any layer of the application without having to handle them explicitly in each controller. The steps are as follows: Install the Symfony/error-handler library. Create a middleware class that implements the Middleware interface. Register the middleware in the application.

PHP exception handling: using Middleware exception handling middleware

Introduction

Exceptions are necessary when we code Face the reality. In PHP, exceptions can be handled using the try-catch statement or set_exception_handler. However, when the business scale grows, these two methods become cumbersome and difficult to maintain. Middleware Exception handling middleware provides an elegant and extensible way to handle exceptions in PHP applications.

What is Middleware?

Middleware is a piece of code that runs between a request and a response. It is responsible for performing actions before or after request processing. Exception handling middleware allows us to handle exceptions at any layer of the application without having to handle them explicitly in every controller or method.

Using Middleware exception handling

Step 1: Installation

composer require symfony/error-handler

Step 2: Create middleware

use Symfony\Component\ErrorHandler\Middleware\ErrorMiddleware;

class ExceptionMiddleware
{
    public function __invoke(Request $request, RequestHandler $handler)
    {
        try {
            return $handler->handle($request);
        } catch (\Exception $e) {
            // 处理异常
            return new Response($e->getMessage(), 500);
        }
    }
}

Step 3: Register middleware

//Slim 4
$app->add(new ExceptionMiddleware());

// Laravel 8+
Route::middleware(['exception_middleware'])->group(function () {
    // ...
});

Practical case

Let us consider a simple CRUD application . When creating a new record, we need to return an error message if the entered date is invalid.

// Controller

// ....

try {
    $entity->setDate($request->get('date'));
} catch (InvalidDateFormatException $e) {
    return new Response($e->getMessage(), 400);
}

Using exception handling middleware, we can separate exception handling from the controller:

// Middleware

class ExceptionMiddleware
{
    public function __invoke(Request $request, RequestHandler $handler)
    {
        try {
            return $handler->handle($request);
        } catch (InvalidDateFormatException $e) {
            // 处理异常
            return new Response(
                json_encode(['error' => $e->getMessage()]),
                400,
                ['Content-Type' => 'application/json']
            );
        }
    }
}

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