bwaidelich/JsonCapableExceptionView.php

## JsonCapableExceptionView.php
<?php
declare(strict_types=1);
namespace Some\Package\Error;

use Neos\Flow\Annotations as Flow;
use Neos\Flow\Http\Helper\ResponseInformationHelper;
use Neos\Flow\Http\Request;
use Neos\Flow\Mvc\Controller\ControllerContext;
use Neos\Flow\Mvc\View\ViewInterface;
use Neos\Utility\MediaTypes;

/**
 * A View that can be used as exception view and that renders exceptions as JSON if the current HTTP request
 * sends a corresponding "Accept" or "Content-Type" header.
 *
 * Example configuration:
 *
 * Flow:
 *   error:
 *     exceptionHandler:
 *       defaultRenderingOptions:
 *         viewClassName: 'Some\Package\Error\JsonCapableExceptionView'
 *         templatePathAndFilename: 'this-is-required'
 *
 * @Flow\Proxy(false)
 */
final class JsonCapableExceptionView implements ViewInterface
{

    /**
     * @var ControllerContext
     */
    private $controllerContext;

    /**
     * @var array
     */
    private $variables = [];

    public static function createWithOptions(array $options): self
    {
        return new static();
    }


    public function setControllerContext(ControllerContext $controllerContext): void
    {
        $this->controllerContext = $controllerContext;
    }

    public function assign($key, $value): self
    {
        $this->variables[$key] = $value;
        return $this;
    }

    public function assignMultiple(array $values): self
    {
        foreach ($values as $key => $value) {
            $this->assign($key, $value);
        }
        return $this;
    }

    public function canRender(ControllerContext $controllerContext): bool
    {
        return true;
    }

    public function render(): string
    {
        $statusCode = $this->variables['statusCode'] ?? 500;
        $referenceCode = $this->variables['referenceCode'] ?? null;
        $statusMessage = ResponseInformationHelper::getStatusMessageByCode($statusCode);
        $referenceCodeMessage = ($referenceCode !== null) ? '<p>When contacting the maintainer of this application please mention the following reference code:<br /><br />' . $referenceCode . '</p>' : '';

        if ($this->isJsonRequest()) {
            header('Content-Type: application/json');
            $error = [
                'message' => $statusMessage,
                'code' => $statusCode,
                'referenceCode' => $referenceCode,
            ];
            return json_encode($error);
        }

        return '<!DOCTYPE html>
			<html>
				<head>
					<meta charset="UTF-8">
					<title>' . $statusCode . ' ' . $statusMessage . '</title>
					<style type="text/css">
						body {
							font-family: Helvetica, Arial, sans-serif;
							margin: 50px;
						}

						h1 {
						    color: #00ADEE;
							font-weight: normal;
						}
					</style>
				</head>
				<body>
                    <h1>' . $statusCode . ' ' . $statusMessage . '</h1>
                    <p>An internal error occurred.</p>
                    ' . $referenceCodeMessage . '
				</body>
			</html>';
    }

    private function isJsonRequest(): bool
    {
        $request = Request::createFromEnvironment();
        $mediaTypeHeader = $request->hasHeader('Accept') && $request->getHeader('Accept') !== '*/*' ? $request->getHeader('Accept') : $request->getHeader('Content-Type');
        if ($mediaTypeHeader === null) {
            return false;
        }
        $mediaType = MediaTypes::parseMediaType($mediaTypeHeader);
        return $mediaType['subtype'] === 'json';
    }
}

## Settings.Error.yaml
Neos:
  Flow:
    error:
      exceptionHandler:
        defaultRenderingOptions:
          viewClassName: 'Some\Package\Error\JsonCapableExceptionView'
          templatePathAndFilename: 'this-is-required'
	<?php
	declare(strict_types=1);
	namespace Some\Package\Error;

	use Neos\Flow\Annotations as Flow;
	use Neos\Flow\Http\Helper\ResponseInformationHelper;
	use Neos\Flow\Http\Request;
	use Neos\Flow\Mvc\Controller\ControllerContext;
	use Neos\Flow\Mvc\View\ViewInterface;
	use Neos\Utility\MediaTypes;

	/**
	* A View that can be used as exception view and that renders exceptions as JSON if the current HTTP request
	* sends a corresponding "Accept" or "Content-Type" header.
	*
	* Example configuration:
	*
	* Flow:
	* error:
	* exceptionHandler:
	* defaultRenderingOptions:
	* viewClassName: 'Some\Package\Error\JsonCapableExceptionView'
	* templatePathAndFilename: 'this-is-required'
	*
	* @Flow\Proxy(false)
	*/
	final class JsonCapableExceptionView implements ViewInterface
	{

	/**
	* @var ControllerContext
	*/
	private $controllerContext;

	/**
	* @var array
	*/
	private $variables = [];

	public static function createWithOptions(array $options): self
	{
	return new static();
	}


	public function setControllerContext(ControllerContext $controllerContext): void
	{
	$this->controllerContext = $controllerContext;
	}

	public function assign($key, $value): self
	{
	$this->variables[$key] = $value;
	return $this;
	}

	public function assignMultiple(array $values): self
	{
	foreach ($values as $key => $value) {
	$this->assign($key, $value);
	}
	return $this;
	}

	public function canRender(ControllerContext $controllerContext): bool
	{
	return true;
	}

	public function render(): string
	{
	$statusCode = $this->variables['statusCode'] ?? 500;
	$referenceCode = $this->variables['referenceCode'] ?? null;
	$statusMessage = ResponseInformationHelper::getStatusMessageByCode($statusCode);
	$referenceCodeMessage = ($referenceCode !== null) ? '<p>When contacting the maintainer of this application please mention the following reference code:<br /><br />' . $referenceCode . '</p>' : '';

	if ($this->isJsonRequest()) {
	header('Content-Type: application/json');
	$error = [
	'message' => $statusMessage,
	'code' => $statusCode,
	'referenceCode' => $referenceCode,
	];
	return json_encode($error);
	}

	return '<!DOCTYPE html>
	<html>
	<head>
	<meta charset="UTF-8">
	<title>' . $statusCode . ' ' . $statusMessage . '</title>
	<style type="text/css">
	body {
	font-family: Helvetica, Arial, sans-serif;
	margin: 50px;
	}

	h1 {
	color: #00ADEE;
	font-weight: normal;
	}
	</style>
	</head>
	<body>
	<h1>' . $statusCode . ' ' . $statusMessage . '</h1>
	<p>An internal error occurred.</p>
	' . $referenceCodeMessage . '
	</body>
	</html>';
	}

	private function isJsonRequest(): bool
	{
	$request = Request::createFromEnvironment();
	$mediaTypeHeader = $request->hasHeader('Accept') && $request->getHeader('Accept') !== '/' ? $request->getHeader('Accept') : $request->getHeader('Content-Type');
	if ($mediaTypeHeader === null) {
	return false;
	}
	$mediaType = MediaTypes::parseMediaType($mediaTypeHeader);
	return $mediaType['subtype'] === 'json';
	}
	}
	Neos:
	Flow:
	error:
	exceptionHandler:
	defaultRenderingOptions:
	viewClassName: 'Some\Package\Error\JsonCapableExceptionView'
	templatePathAndFilename: 'this-is-required'