How to override protected _prepareLayout function in block in Magento 2?

Question

I wanted to make changes in _prepareLayout() in block. Code is as follow:

Block: Magento\Catalog\Block\Category\View

protected function _prepareLayout()
{
    parent::_prepareLayout();

    $this->getLayout()->createBlock(\Magento\Catalog\Block\Breadcrumbs::class);

    $category = $this->getCurrentCategory();
    if ($category) {
        $title = $category->getMetaTitle();
        if ($title) {
            $this->pageConfig->getTitle()->set($title);
        }
        $description = $category->getMetaDescription();
        if ($description) {
            $this->pageConfig->setDescription($description);
        }
        $keywords = $category->getMetaKeywords();
        if ($keywords) {
            $this->pageConfig->setKeywords($keywords);
        }
        if ($this->_categoryHelper->canUseCanonicalTag()) {
            $this->pageConfig->addRemotePageAsset(
                $category->getUrl(),
                'canonical',
                ['attributes' => ['rel' => 'canonical']]
            );
        }

        $pageMainTitle = $this->getLayout()->getBlock('page.main.title');
        if ($pageMainTitle) {
            $pageMainTitle->setPageTitle($this->getCurrentCategory()->getName());
        }
    }

    return $this;
}

As per above code, I want to make change in below data:

if ($this->_categoryHelper->canUseCanonicalTag()) {
      $this->pageConfig->addRemotePageAsset(
          $category->getUrl(),
          'canonical',
          ['attributes' => ['rel' => 'canonical']]
      );
}

Help me to change the parameter passed to addRemotePageAsset() by overriding block.

Answer 1

you can not override protected methods in Magento 2, only the public method can be overridden using plugin or preference. there is no way to override protected and private method in Magento 2.

Answer 2

In your custom module (lets assume the module is in app/code/Extend/Simple)

etc/di.xml

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:ObjectManager/etc/config.xsd">
    <preference for="Magento\Catalog\Block\Category\View" type="Extend\Simple\Block\CategoryView" />
</config>

create class "CategoryView" under Extend\Simple\Block

<?php declare(strict_types=1);

namespace Extend\Simple\Block;

class CategoryView extends \Magento\Catalog\Block\Category\View
{
    protected function _prepareLayout()
    {
       //Your function goes here
    }
}

run setup upgrade

or

cache flush & setup di compile