Can't declare class symfony 3 - php

Question

i got a little error trying to implement a MaintenanceListener service, who will display a maintenance page
Here's my services.yml
# https://symfony.com/doc/current/service_container.html
services:
# default configuration for services in *this* file
_defaults:
# automatically injects dependencies in your services
autowire: true
# automatically registers your services as commands, event subscribers, etc.
autoconfigure: true
# this means you cannot fetch services directly from the container via $container->get()
# if you need to do this, you can override this setting on individual services
public: false
# makes classes in Cocorico\CoreBundle\DataFixtures\ORM\ available to be used as services
# this creates a service per class whose id is the fully-qualified class name
# Cocorico\CoreBundle\DataFixtures\ORM\:
# resource: '../../src/Cocorico/CoreBundle/DataFixtures/ORM/*'
# makes classes in src/AppBundle available to be used as services
# this creates a service per class whose id is the fully-qualified class name
AppBundle\:
resource: '../../src/AppBundle/*'
# you can exclude directories or files
# but if a service is unused, it's removed anyway
exclude: '../../src/AppBundle/{Entity,Repository,Tests,Event}'
# controllers are imported separately to make sure they're public
# and have a tag that allows actions to type-hint services
# AppBundle\Controller\:
# resource: '../../src/AppBundle/Controller'
# public: true
# tags: ['controller.service_arguments']
# add more services, or override services that need manual wiring
# AppBundle\Service\ExampleService:
# arguments:
# $someArgument: 'some_value'
maintenance_listener:
class: AppBundle\Event\MaintenanceListener
arguments:
tags:
- { name: kernel.event_listener, event: kernel.request, method: onKernelRequest }```
Here's my class:
<?php
namespace MListener;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\HttpFoundation\Response;
class MListener
{
public function onKernelRequest(GetResponseEvent $event)
{
$event->setResponse(new Response('Iziparty is in maintenance mode', Response::HTTP_SERVICE_UNAVAILABLE));
$event->stopPropagation();
}
}
and here's the error i get:
FastCGI sent in stderr: "PHP message: PHP Fatal error: Cannot declare class MListener\MListener, because the name is already in use in /var/www/Symfony/src/AppBundle/Event/MaintenanceListener.php on line 9" while reading response header from upstream
Thanks for the help.

Answer 1

it all comes down to autoload magic. The autoload magic assumes a certain directory structure, that is (among other things) defined in composer.json. It essentially says:
namespace AppBundle\... is in directory src/AppBundle/...
and every class AppBundle\Something\Else is therefore located in src/AppBundle/Something/Else.php
now, symfony starts to load the service that is supposed to handle an event (due to your configuration) AppBundle\Event\MaintenanceListener, which it tries to instantiate, which leads to the auto loader loading the file src/AppBundle/Event/MaintenanceListener.php which only contains the class MListener/MListener.
Since auto-loading is a bit hacky, usually, it will try other approaches / definitions and possibly try to read that file again and it'll then fail to re-declare the MListener/MListener class, since it already exists.
Just to be explicit about this: These approaches work very well if standards are followed (specifically PSR-4 in this case), which bind the directory structure to namespace structure. If you put something in a file, that - according to PSR-4 - doesn't belong there, you gonna get problems, like the one you got.
The fix is easy and obvious: namespace is the directory (with backslash instead of whatever directory separator your OS has), filename is the classname (without .php obviously). So either, rename your file to src/MListener/MListener.php and adapt the services.yaml accordingly: MListener\Mlistener: ... or you rename your namespace and class in that file to AppBundle\Event and MaintenanceListener respectively.

Answer 2

Be sure to create the file src/Event/MaintenanceListener.php
<?php
namespace AppBundle\Event;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
use Symfony\Component\HttpFoundation\Response;
class MaintenanceListener
{
public function onKernelRequest(GetResponseEvent $event)
{
$event->setResponse(new Response('Iziparty is in maintenance mode', Response::HTTP_SERVICE_UNAVAILABLE));
$event->stopPropagation();
}
}
With same name declared in the file service.yaml