如何在ZF2中从EVENT_DISPATCH事件中抛出异常

Question

I would like to throw an exception from within the EVENT_DISPATCH event that gets handled identical to how it would have been handled had it been thrown from a controllers dispatch method. However I have no clue how to do so.

In the first piece of code the exception is not caught and no EVENT_DISPATCH_ERROR is triggered. I tried to play with the MvcEvent::setError method but no clue there.

$this->listeners[] = $events->attach(MvcEvent::EVENT_DISPATCH, array($this, 'onDispatch'), 100);


public function onDispatch(MvcEvent $e)
{
    if ($condition) {
        throw SomeException;
    }
}

versus

class Controller extends AbstractActionController
{
    public function onDispatch(MvcEvent $e)
    {
        if ($condition) {
            throw SomeException;
        }
    }
}

Answer 1

I'm not sure that what you are trying to do is 100% possible. You can get close, however.

The issue arises from the fact that ZF2 handles controller exceptions as an event, and the event manager determines what to do with those exceptions. As you are throwing an exception from the event manager itself, it can't be handled in the same way as a controller exception.

One possible solution is to set a global exception handler in php:

public function onBootstrap( MvcEvent $e )
{
    $eventManager = $e->getApplication()->getEventManager();
    $eventManager->attach( MvcEvent::EVENT_DISPATCH, array( $this, 'onDispatch' ) );

    //set the global exception handler
    set_exception_handler( array( $this, 'handleException' ) );
}

public function onDispatch( MvcEvent $e )
{
    if ( true )
    {
        throw new \Exception();
    }
}

public function handleException( \Exception $e )
{
    //do something with the exception
}

However, there are some drawbacks to taking this approach, as this will override the default handling of ALL exceptions in your application, so you may want to only allow it to handle specific exceptions and let the default handler support the rest, so:

public function handleException( \Exception $e )
{
    if ( $e instanceof MyExceptionClass )
    {
        //do something with the exception
    }
    else
    {
        //rethrow the exception
        throw $e;
    }
}

For more on this you can read the comments in the php docs: http://php.net/manual/en/function.set-exception-handler.php#usernotes