Magento 2: How to Improve Code In Magento (PHP)?

Question

I'm new to Magento just, I'm working on an event I call many files through object manager, but I know that's not a good way, I have a chunk of code just need to know how can I improve it.

CustomerAddress\Attribute\Observer

<?php
namespace CustomerAddress\Attribute\Observer;

use Magento\Framework\Event\ObserverInterface;

class AfterPlaceObserver implements ObserverInterface
{
    protected $addressRepository;

    protected $addressFactory;

    protected $checkoutSession;

    protected $orderFactory;

    protected $jsonHelper;

    public function __construct(
        \Magento\Customer\Api\AddressRepositoryInterface $addressRepository,
        \Magento\Customer\Model\AddressFactory $addressFactory,
        \Magento\Checkout\Model\Session $checkoutSession,
        \Magento\Sales\Model\OrderFactory $orderFactory,
        \Magento\Framework\Json\Helper\Data $jsonHelper
    ) {
        $this->addressRepository = $addressRepository;
        $this->addressFactory = $addressFactory;
        $this->checkoutSession = $checkoutSession;
        $this->orderFactory = $orderFactory;
        $this->jsonHelper = $jsonHelper;
    }

    public function execute(\Magento\Framework\Event\Observer $observer)
    {

        $objectManager          = \Magento\Framework\App\ObjectManager::getInstance();
        // $addressRepository      = $objectManager->create('\Magento\Customer\Api\AddressRepositoryInterface');
        // $addressFactory         = $objectManager->create('\Magento\Customer\Model\AddressFactory');
        // $checkoutSession        = $objectManager->create('\Magento\Checkout\Model\Session');
        // $orderFactory           = $objectManager->create('\Magento\Sales\Model\OrderFactory');
        // $jsonHelper             = $objectManager->create('\Magento\Framework\Json\Helper\Data');

        $orderIncrementId       = $checkoutSession->getLastRealOrderId();
        $orderInfo              = $objectManager->create('Magento\Sales\Model\Order')->loadByIncrementId($orderIncrementId);

        $bssCustomfield         = $orderInfo->getBssCustomfield();
        $jsonBssCustomfield     = $jsonHelper->jsonDecode($bssCustomfield);
        $jsonTaxExemptNumber    = $jsonBssCustomfield['tax_exempt_number']['value'];

        $addressRepository      = $objectManager->create('\Magento\Customer\Api\AddressRepositoryInterface');
        $addressObject          = $addressRepository->getById($orderInfo->getShippingAddress()->getCustomerAddressId());
        $addressObject->setCustomAttribute('customer_tax_exempt_number', $jsonTaxExemptNumber);
        $addressRepository->save($addressObject);
    }

}

Answer 1

Dependency injection

Without Object Manager Your Code is Look Like This :-

<?php
namespace CustomerAddress\Attribute\Observer;

use Magento\Framework\Event\ObserverInterface;

class AfterPlaceObserver implements ObserverInterface
{
    protected $addressRepository;

    protected $addressFactory;

    protected $checkoutSession;

    protected $order;

    protected $jsonHelper;

    public function __construct(
        \Magento\Customer\Api\AddressRepositoryInterface $addressRepository,
        \Magento\Customer\Model\AddressFactory $addressFactory,
        \Magento\Checkout\Model\Session $checkoutSession,
        \Magento\Sales\Model\Order $order,
        \Magento\Framework\Json\Helper\Data $jsonHelper
    ) {
        $this->addressRepository = $addressRepository;
        $this->addressFactory = $addressFactory;
        $this->checkoutSession = $checkoutSession;
        $this->order = $order;
        $this->jsonHelper = $jsonHelper;
    }
    public function execute(\Magento\Framework\Event\Observer $observer)
    {
        $orderIncrementId       = $this->checkoutSession->getLastRealOrderId();
        $orderInfo              = $this->order->loadByIncrementId($orderIncrementId);

        $bssCustomfield         = $orderInfo->getBssCustomfield();
        $jsonBssCustomfield     = $this->jsonHelper->jsonDecode($bssCustomfield);
        $jsonTaxExemptNumber    = $jsonBssCustomfield['tax_exempt_number']['value'];

        $addressRepository      = $this->addressRepository;
        $addressObject          = $addressRepository->getById($orderInfo->getShippingAddress()->getCustomerAddressId());
        $addressObject->setCustomAttribute('customer_tax_exempt_number', $jsonTaxExemptNumber);
        $addressRepository->save($addressObject);
    }

}