New ordering function in product lists pages based on Qty (Sort by Stock) in Magento 2.4.x

Question

I want to Implement a new ordering function to order products in product lists pages based on Qty (Stock). I tried but something goes wrong. Help me out.

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\Catalog\Model\Layer">
        <plugin name="product_sort_by_stock" type="Company\Module\Model\Plugin\Layer"/>
    </type>
</config>

....\Plugin\Catalog\Block

class SortStock
{

    const STOCK_SORT_BY = 'qty';

    public function afterGetAttributeUsedForSortByArray(Config $subject, $result)
    {
        return array_merge($result, [self::STOCK_SORT_BY => __('Qty')]);
    }

    
    public function beforeSetCollection(Toolbar $subject, Collection $collection)
    {

        if ($subject->getCurrentOrder() === self::STOCK_SORT_BY) {

            $collection->getSelect()->joinLeft(
                array('_inv' => $collection->getResource()->getTable('cataloginventory_stock_status')),
                "_inv.product_id = e.entity_id",
                array('stock_status')
            );
            $collection->addExpressionAttributeToSelect('in_stock', 'IFNULL(_inv.stock_status,0)', array());
            $collection->getSelect()->reset('order');
            $collection->getSelect()->order('in_stock DESC');

        }
    }
}

Answer 1

Use <plugin name="product_sort_by_stock" type="Company\Module\Model\Plugin\Layer"/>

to

<plugin name="product_sort_by_stock" type="Company\Module\Model\Plugin\Catalog\Block\SortStock"/>.

Thank You!

Answer 2

This is how I have fixed this one. It would help others.

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\Catalog\Model\Layer">
        <plugin name="product_sort_by_stock" type="Company\Vendor\Model\Plugin\Layer"/>
    </type>
    <type name="Magento\Catalog\Model\Config">
        <plugin name="after_get_available_orders" type="Company\Vendor\Model\Plugin\Layer"/>
    </type>
</config>

Company\Module\Model\Plugin\Layer.php

<?php

namespace Company\Vendor\Model\Plugin;
use Magento\Catalog\Model\Config;
use Magento\Framework\Data\Collection;

class Layer
{
    /**
     * Stock Quantity sorting attribute
     */

    const STOCK_SORT_BY = 'stock_status';

    /**
     * @param Config $subject
     * @param $result
     * @return mixed
     */
    public function afterGetAttributeUsedForSortByArray(Config $subject, $result)
    {
        return array_merge($result, [self::STOCK_SORT_BY => __('Stock Qty')]);
    }

    /**
     * Collection to get data sort from stock qty
     *
     * @param \Magento\Catalog\Model\Layer $subject
     * @param Collection $collection
     * @return void
     */
    public function beforeSetCollection(\Magento\Catalog\Model\Layer $subject, Collection $collection)
    {
        if ($subject->getCurrentOrder() === self::STOCK_SORT_BY) {

            $setDirection = $subject->getCurrentDirection();
            $collection->getSelect()->joinLeft(
                array('_stockqty' => $collection->getResource()->getTable('cataloginventory_stock_status')),
                "_stockqty.product_id = e.entity_id",
                array('stock_status')
            );
            $collection->addExpressionAttributeToSelect('in_stock', 'IFNULL(_stockqty.stock_status,0)', array());
            $collection->getSelect()->reset('order');
            $collection->getSelect()->setOrder('in_stock ' .$setDirection);
            return $collection->getData();
        }
    }
}