Around Plugin produce error in generateXml method for sitemap

Question

I need to change the functionality of the generating sitemap xml. For that, I used around plugin for the generateXml() method in the Magento\Sitemap\Model\Sitemap class. When I try to generate the file, the filename to be generated is coming as empty. So it produces exceptional error. How can we resolve it?

my 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">
    <type name="Magento\Sitemap\Model\Sitemap">
        <plugin name="SitemapSplitter" type="Company\SitemapSplitter\Model\Sitemap" sortOrder="1"/>
    </type>
</config>

Company\SitemapSplitter\Model\Sitemap.php

<?php
namespace Company\SitemapSplitter\Model;
use Magento\Framework\App\Filesystem\DirectoryList;
use Magento\Framework\Model\AbstractModel;
class Sitemap extends \Magento\Sitemap\Model\Sitemap {

public function aroundGenerateXml(\Magento\Sitemap\Model\Sitemap $subject, \Closure $proceed, $requestInfo = null)
    {
      $this->_initSitemapItems();
        /** @var $sitemapItem \Magento\Framework\DataObject */
        foreach ($this->_sitemapItems as $sitemapItem) {
            $changefreq = $sitemapItem->getChangefreq();
            $priority = $sitemapItem->getPriority();
            foreach ($sitemapItem->getCollection() as $item) {
                $xml = $this->_getSitemapRow(
                    $item->getUrl(),
                    $item->getUpdatedAt(),
                    $changefreq,
                    $priority,
                    $item->getImages()
                );
                if ($this->_isSplitRequired($xml) && $this->_sitemapIncrement > 0) {
                    $this->_finalizeSitemap();
                }
                if (!$this->_fileSize) {
                    $this->_createSitemap();
                }
                $this->_writeSitemapRow($xml);
                // Increase counters
                $this->_lineCount++;
                $this->_fileSize += strlen($xml);
            }
        }
        $this->_finalizeSitemap();

        if ($this->_sitemapIncrement == 1) {
            // In case when only one increment file was created use it as default sitemap
            $path = rtrim(
                $this->getSitemapPath(),
                '/'
            ) . '/' . $this->_getCurrentSitemapFilename(
                $this->_sitemapIncrement
            );
            $destination = rtrim($this->getSitemapPath(), '/') . '/' . $this->getSitemapFilename();

            $this->_directory->renameFile($path, $destination);
        } else {
            // Otherwise create index file with list of generated sitemaps
            $this->_createSitemapIndex();
        }

        // Push sitemap to robots.txt
        if ($this->_isEnabledSubmissionRobots()) {
            $this->_addSitemapToRobotsTxt($this->getSitemapFilename());
        }

        $this->setSitemapTime($this->_dateModel->gmtDate('Y-m-d H:i:s'));
        $this->save();

        return $this;
    }
}
?>

Answer 1

From the Magento\Sitemap\Model\Sitemap I can see that _initSitemapItems , _sitemapItems and many things are protected members and in plugin I think we can not access it by $this (and for public members we can access it by $subject object ). So I think you have to overwrite this method with the help of di.xml