Magento2 Event interception not working

Question

I want to intercept sales_order_place_before event, so I created a new module named app\code\Giulio\CheckoutExtention, created aregistration.php` file where I put this code below:

<?php
\Magento\Framework\Component\ComponentRegistrar::register(
    \Magento\Framework\Component\ComponentRegistrar::MODULE,
    'Giulio_CheckoutExtension',
    __DIR__
);

a module.xml inside app\code\Giulio\CheckoutExtention\etcwhere I have declared my module like following:

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd" >
    <module name="Giulio_CheckoutExtension" setup_version="0.0.1"/>
</config>

and then always inside \etc folder, an events.xmlwhere i declared my Observer like this.

<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Event/etc/events.xsd">
    <event name="sales_order_place_after">
        <observer name="set_checkout_if_no_different_categories" instance="Giulio\CheckoutExtension\Observer\SetCheckout" />
    </event>
</config>

Then inside \Giulio\CheckoutExtension\Observer a SetCheckout.php file where I extended Monolog\Logger class for loggin some messages and implemented ObserverInterface like this:

<?php

namespace Giulio\CheckoutExtension\Observer;

use Magento\Framework\Event\Observer;
use Monolog\Logger;

class SetCheckout extends Logger implements \Magento\Framework\Event\ObserverInterface {



    public function execute(Observer $observer) {
        $order = $observer->getEvent()->getOrder();
        $order->setOrderId("CIAO");
        $this->warning("Ho creato un Log con l'observer");
    }
}

after executing

rm -rf var/di/* var/generation/* var/cache/* var/log/* var/page_cache/*

php bin/magento cache:clean

php bin/magento cache:flush

php bin/magento setup:upgrade

php bin/magento setup:di:compile

php bin/magento indexer:reindex

and tried to accessing Homepage for my store, the page wont load and it will be left blank.

Any suggestion?

Thanks you all anticipately!

Answer 1

Replace your code with below the code. it will resolve your issue.

<?php

namespace Giulio\CheckoutExtension\Observer;

use Magento\Framework\Event\Observer;

class SetCheckout implements \Magento\Framework\Event\ObserverInterface {
    public $_logger;
    public function __construct(
        \Psr\Log\LoggerInterface $logger

    ) {
        $this->_logger = $logger;        
    }

    public function execute(Observer $observer) {
        $order = $observer->getEvent()->getOrder();
        $order->setOrderId("CIAO");
        $this->_logger->warning("Ho creato un Log con l'observer");
    }
}