404 listener in ZF2

Module.php

<?php
class Module
{
    public function onBootstrap($e)
    {
        $app = $e->getApplication();
        $events = $app->getEventManager();

        // Direct instantiation
        $events->attach(new RouteNotFoundListener());

        // Or pull from service container, assuming you've registered it
        $services = $app->getServiceManager();
        $events->attach($services->get('RouteNotFoundListener'));
    }
}

RouteNotFoundListener.php

<?php
use Zend\EventManager\AbstractListenerAggregate;
use Zend\EventManager\EventManagerInterface;
use Zend\Mvc\Application;
use Zend\Mvc\Router\RouteMatch;

class RouteNotFoundListener extends AbstractListenerAggregate
{
    public function attach(EventManagerInterface $events)
    {
        $events->attach('dispatch.error', array($this, 'onDispatchError'), 1000);
    }

    public function onDispatchError($e)
    {
        if ($e->getError() !== Application::ERROR_ROUTER_NO_MATCH) {
            // Not a 404 error
            return;
        }

        $e->setError(false);

        $e->setRouteMatch(new RouteMatch(array(
            'controller' => 'SomeCustomErrorController',
            'action'     => 'actionMethodIfAny',
            /* ... other params? ...*/
        )));

        $e->stopPropagation(true);
    }
}

The last two lines are added to make this work

<?php
namespace ErrorApi\V1\Rest\Listeners;

use Zend\EventManager\AbstractListenerAggregate;
use Zend\EventManager\EventManagerInterface;
use Zend\Mvc\Application;
use Zend\Mvc\Router\RouteMatch;
class RouteNotFoundListener extends AbstractListenerAggregate
{
    public function attach(EventManagerInterface $events)
    {
        $events->attach('dispatch.error', array($this, 'onDispatchError'), 1000);
    }

    public function onDispatchError($e)
    {
        $eventManager = $e->getApplication()->getEventManager();
        if ($e->getError() !== Application::ERROR_ROUTER_NO_MATCH) {
            // Not a 404 error
            return;
        }
        $newRouteMatch = new RouteMatch(array('controller' => 'ErrorApi\V1\Rest\Error\Controller')); 
        $e->setRouteMatch($newRouteMatch);
        $eventManager->trigger('dispatch', $e);
    }
}

@ppeiris Actually, that's not a great solution, as it does not mimic the event loop within the application perfectly (it doesn't trigger the finish event, and thus the view may not get rendered, etc.).

I've updated the gist to do the following:

• Push the route match into the event
• Clear the error in the event
• Stop propagation of the event (because at this point, we know we need to handle a 404; there's no further handlers we should fire)