How to throw an exception in your Extension?

Question

In an Extbase extension, the need may arise to inform the user about an error or exception.

In my case, I have to parse some data from a potentially bad source. So the extension has to validate this data. And if the data is invalid, it needs to throw an exception that then can be handled by TYPO3.

However, I can only find information about how the exception and error handlers works, but no information on how to correctly throw an exception from inside an extension.

So what is the intended way to throw an exception from inside an Extbase extension?

Expected result

If I produce a syntax error, TYPO3 displays a message similar to this: (Taken from the core API reference.)

That is what I would expect a correctly thrown error or exception to look like.

What I tried

Edit: I tried throwing an error like this:

throw new \Exception('Invalid data');

However, all the frontend displays is

Oops, an error occurred! Code: 20160721101726b5339896

Another possible way to produce an error:

$GLOBALS['TSFE']->pageNotFoundAndExit('Invalid data');

However, this shows a Page Not Found error instead of the expected exception.

Answer 1

namespace VendorName\ExtensionName\Controller;

abstract class ActionController extends \TYPO3\CMS\Extbase\Mvc\Controller\ActionController {
    /**
     * @var string
     */
    protected $entityNotFoundMessage = 'The requested entity could not be found.';

    /**
     * @var string
     */
    protected $unknownErrorMessage = 'An unknown error occurred. The wild monkey horde in our basement will try to fix this as soon as possible.';

    /**
     * @param \TYPO3\CMS\Extbase\Mvc\RequestInterface $request
     * @param \TYPO3\CMS\Extbase\Mvc\ResponseInterface $response
     * @return void
     * @throws \Exception
     * @override \TYPO3\CMS\Extbase\Mvc\Controller\ActionController
     */
    public function processRequest(\TYPO3\CMS\Extbase\Mvc\RequestInterface $request, \TYPO3\CMS\Extbase\Mvc\ResponseInterface $response) {
        try {
            parent::processRequest($request, $response);
        }
        catch(\Exception $exception) {
            // If the property mapper did throw a \TYPO3\CMS\Extbase\Property\Exception, because it was unable to find the requested entity, call the page-not-found handler.
            $previousException = $exception->getPrevious();
            if (($exception instanceof \TYPO3\CMS\Extbase\Property\Exception) && (($previousException instanceof \TYPO3\CMS\Extbase\Property\Exception\TargetNotFoundException) || ($previousException instanceof \TYPO3\CMS\Extbase\Property\Exception\InvalidSourceException))) {
                $GLOBALS['TSFE']->pageNotFoundAndExit($this->entityNotFoundMessage);
            }
            throw $exception;
        }
    }

    /**
     * @return void
     * @override \TYPO3\CMS\Extbase\Mvc\Controller\ActionController
     */
    protected function callActionMethod() {
        try {
            parent::callActionMethod();
        }
        catch(\Exception $exception) {
            // This enables you to trigger the call of TYPO3s page-not-found handler by throwing \TYPO3\CMS\Core\Error\Http\PageNotFoundException
            if ($exception instanceof \TYPO3\CMS\Core\Error\Http\PageNotFoundException) {
                $GLOBALS['TSFE']->pageNotFoundAndExit($this->entityNotFoundMessage);
            }

            // $GLOBALS['TSFE']->pageNotFoundAndExit has not been called, so the exception is of unknown type.
            \VendorName\ExtensionName\Logger\ExceptionLogger::log($exception, $this->request->getControllerExtensionKey(), \VendorName\ExtensionName\Logger\ExceptionLogger::SEVERITY_FATAL_ERROR);
            // If the plugin is configured to do so, we call the page-unavailable handler.
            if (isset($this->settings['usePageUnavailableHandler']) && $this->settings['usePageUnavailableHandler']) {
                $GLOBALS['TSFE']->pageUnavailableAndExit($this->unknownErrorMessage, 'HTTP/1.1 500 Internal Server Error');
            }
            // Else we append the error message to the response. This causes the error message to be displayed inside the normal page layout. WARNING: the plugins output may gets cached.
            if ($this->response instanceof \TYPO3\CMS\Extbase\Mvc\Web\Response) {
                $this->response->setStatus(500);
            }
            $this->response->appendContent($this->unknownErrorMessage);
        }
    }
}

Here is an article that explains that. However like most of articles about TYPO3 Programming is in German ;-)

http://nerdcenter.de/extbase-fehlerbehandlung/