Refactoring the conversion of exceptions

Author: Florian Krämer

readme.md

@@ -17,11 +17,9 @@ composer require phauthentic/problem-details-symfony-bundle
 ```php
 class ExampleController
 {
-    private ProblemDetailsFactoryInterface $problemDetailsFactory;
-
-    public function __construct(ProblemDetailsFactoryInterface $problemDetailsFactory)
-    {
-        $this->problemDetailsFactory = $problemDetailsFactory;
+    public function __construct(
+        private ProblemDetailsFactoryInterface $problemDetailsFactory
+    ) {
     }
 
     /**
@@ -33,8 +31,10 @@ class ExampleController
             type: 'https://example.net/validation-error',
             detail: 'Your request is not valid.',
             status: 422,
+            title: 'Validation Error',
         );
     }
+}
 ```
 
 ## Problem Details Example

src/ExceptionConversion/ExceptionConverterInterface.php

@@ -0,0 +1,22 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Phauthentic\Symfony\ProblemDetails\ExceptionConversion;
+
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Throwable;
+
+/**
+ * Handles Thowable and converts them into a Problem Details HTTP response.
+ *
+ * Notice that you might need to adjust the priority of the listener in your services.yaml file to make sure it is
+ * executed in the right order if you have other listeners.
+ */
+interface ExceptionConverterInterface
+{
+    public function canHandle(Throwable $throwable): bool;
+
+    public function convertExceptionToErrorDetails(Throwable $throwable, ExceptionEvent $event): Response;
+}

src/ExceptionConversion/GenericThrowableConverter.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Phauthentic\Symfony\ProblemDetails\ExceptionConversion;
+
+use Phauthentic\Symfony\ProblemDetails\ProblemDetailsFactoryInterface;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Throwable;
+
+/**
+ * Handles Thowable and converts it into a Problem Details HTTP response.
+ *
+ * Notice that you might need to adjust the priority of the listener in your services.yaml file to make sure it is
+ * executed in the right order if you have other listeners.
+ *
+ * <code>
+ * Phauthentic\Symfony\ProblemDetails\ThrowableToProblemDetailsKernelListener:
+ *      arguments: ['%kernel.environment%', { }]
+ *      tags:
+ *          - { name: kernel.event_listener, event: kernel.exception, priority: -20 }
+ * </code>
+ *
+ * @link https://www.rfc-editor.org/rfc/rfc9457.html
+ */
+class GenericThrowableConverter implements ExceptionConverterInterface
+{
+    /**
+     * @param ProblemDetailsFactoryInterface $problemDetailsFactory
+     * @param string $environment
+     * @param array<callable> $mappers
+     */
+    public function __construct(
+        protected ProblemDetailsFactoryInterface $problemDetailsFactory,
+        protected string $environment = 'prod',
+        protected array $mappers = []
+    ) {
+    }
+
+    public function canHandle(Throwable $throwable): bool
+    {
+        return true;
+    }
+
+    public function convertExceptionToErrorDetails(Throwable $throwable, ExceptionEvent $event): Response
+    {
+        $extensions = [];
+        if ($this->environment === 'dev' || $this->environment === 'test') {
+            $extensions['trace'] = $throwable->getTrace();
+        }
+
+        return $this->problemDetailsFactory->createResponse(
+            status: Response::HTTP_INTERNAL_SERVER_ERROR,
+            title: $throwable->getMessage(),
+            extensions: $extensions,
+        );
+    }
+}

src/ExceptionConversion/HttpExceptionConverter.php

@@ -0,0 +1,43 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Phauthentic\Symfony\ProblemDetails\ExceptionConversion;
+
+use Phauthentic\Symfony\ProblemDetails\ProblemDetailsFactoryInterface;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\Exception\HttpException;
+use Throwable;
+
+/**
+ * Handles Symfony\Component\HttpKernel\Exception\HttpException exceptions and converts them into Problem Details HTTP
+ * responses.
+ *
+ * Notice that you might need to adjust the priority of the order in your services.yaml file to make sure it is
+ * executed in the right order if you have other converters.
+ *
+ * @link https://www.rfc-editor.org/rfc/rfc9457.html
+ */
+class HttpExceptionConverter implements ExceptionConverterInterface
+{
+    public function __construct(
+        protected ProblemDetailsFactoryInterface $problemDetailsFactory
+    ) {
+    }
+
+    public function canHandle(Throwable $throwable): bool
+    {
+        return $throwable instanceof HttpException;
+    }
+
+    public function convertExceptionToErrorDetails(Throwable $throwable, ExceptionEvent $event): Response
+    {
+        /** @var HttpException $throwable */
+        return $this->problemDetailsFactory->createResponse(
+            status: $throwable->getStatusCode(),
+            type: 'https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/' . $throwable->getStatusCode(),
+            title: $throwable->getMessage()
+        );
+    }
+}

src/ExceptionConversion/ValidationFailedExceptionConverter.php

@@ -0,0 +1,59 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Phauthentic\Symfony\ProblemDetails\ExceptionConversion;
+
+use Phauthentic\Symfony\ProblemDetails\FromExceptionEventFactoryInterface;
+use Phauthentic\Symfony\ProblemDetails\Validation\ValidationErrorsBuilder;
+use RuntimeException;
+use Symfony\Component\HttpFoundation\Response;
+use Symfony\Component\HttpKernel\Event\ExceptionEvent;
+use Symfony\Component\HttpKernel\Exception\HttpException;
+use Symfony\Component\HttpKernel\Exception\UnprocessableEntityHttpException;
+use Symfony\Component\Validator\Exception\ValidationFailedException;
+use Throwable;
+
+/**
+ * Notice that you might need to adjust the priority of the order in your services.yaml file to make sure it is
+ * executed in the right order if you have other converters.
+ */
+class ValidationFailedExceptionConverter implements ExceptionConverterInterface
+{
+    public function __construct(
+        protected ValidationErrorsBuilder $validationErrorsBuilder,
+        protected FromExceptionEventFactoryInterface $problemDetailsResponseFactory
+    ) {
+    }
+
+    public function canHandle(Throwable $throwable): bool
+    {
+        if ($throwable instanceof UnprocessableEntityHttpException) {
+            $throwable = $throwable->getPrevious();
+        }
+
+        return $throwable instanceof ValidationFailedException;
+    }
+
+    private function extractValidationFailedException(Throwable $throwable): ValidationFailedException
+    {
+        if ($throwable instanceof UnprocessableEntityHttpException) {
+            $throwable = $throwable->getPrevious();
+        }
+
+        if ($throwable instanceof ValidationFailedException) {
+            return $throwable;
+        }
+
+        throw new RuntimeException('ValidationFailedException not found');
+    }
+
+    public function convertExceptionToErrorDetails(Throwable $throwable, ExceptionEvent $event): Response
+    {
+        $throwable = $this->extractValidationFailedException($throwable);
+
+        $errors = $this->validationErrorsBuilder->buildErrors($throwable);
+
+        return $this->problemDetailsResponseFactory->createResponseFromKernelExceptionEvent($event, $errors);
+    }
+}

src/HttpExceptionToProblemDetailsKernelListener.php

@@ -4,15 +4,14 @@
 
 namespace Phauthentic\Symfony\ProblemDetails;
 
-use Symfony\Component\HttpFoundation\JsonResponse;
-use Symfony\Component\HttpFoundation\Response;
+use InvalidArgumentException;
+use Phauthentic\Symfony\ProblemDetails\ExceptionConversion\ExceptionConverterInterface;
 use Symfony\Component\HttpKernel\Event\ExceptionEvent;
-use Throwable;
 
 /**
  * Handles Thowable and converts it into a Problem Details HTTP response.
  *
- * Notice that you might need to adjust the priority of the listener in your services.yaml file to make sure it is
+ * Notice that you might need to adjust the priority of the converters in your services.yaml file to make sure it is
  * executed in the right order if you have other listeners.
  *
  * <code>
@@ -27,15 +26,14 @@
 class ThrowableToProblemDetailsKernelListener
 {
     /**
-     * @param ProblemDetailsFactoryInterface $problemDetailsFactory
-     * @param string $environment
-     * @param array<callable> $mappers
+     * @param array<ExceptionConverterInterface> $exceptionConverters
      */
     public function __construct(
-        protected ProblemDetailsFactoryInterface $problemDetailsFactory,
-        protected string $environment = 'prod',
-        protected array $mappers = []
+        protected array $exceptionConverters = []
     ) {
+        if (empty($this->exceptionConverters)) {
+            throw new InvalidArgumentException('No exception converter passed!');
+        }
     }
 
     public function onKernelException(ExceptionEvent $event): void
@@ -44,37 +42,26 @@ public function onKernelException(ExceptionEvent $event): void
             return;
         }
 
-        $throwable = $event->getThrowable();
+        $this->processConverters($event);
+    }
 
-        $class = get_class($throwable);
-        if (isset($this->mappers[$class])) {
-            $mapper = $this->mappers[$class];
-            $response = $mapper($throwable);
+    private function processConverters(ExceptionEvent $event): void
+    {
+        $throwable = $event->getThrowable();
+        foreach ($this->exceptionConverters as $exceptionConverter) {
+            if (!$exceptionConverter->canHandle($throwable)) {
+                continue;
+            }
 
+            $response = $exceptionConverter->convertExceptionToErrorDetails($throwable, $event);
             $event->setResponse($response);
 
             return;
         }
-
-        $event->setResponse($this->buildResponse($throwable));
     }
 
     private function isNotAJsonRequest(ExceptionEvent $event): bool
     {
         return $event->getRequest()->getPreferredFormat() !== 'json';
     }
-
-    private function buildResponse(Throwable $throwable): Response
-    {
-        $extensions = [];
-        if ($this->environment === 'dev' || $this->environment === 'test') {
-            $extensions['trace'] = $throwable->getTrace();
-        }
-
-        return $this->problemDetailsFactory->createResponse(
-            status: Response::HTTP_INTERNAL_SERVER_ERROR,
-            title: $throwable->getMessage(),
-            extensions: $extensions
-        );
-    }
 }