I need filter products by discount percentage in layared navigation (category page)

Question

I have applied several price cart rules, I would like to see those frontend rules that work as a filter for discounted products. Someone can help me?

Answer 1

For filter products by discount percentage follow below steps:

1.Create the registration.php file

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

2.Create the Vendor/DiscountFilter/etc/module.xml file

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" 
        xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="Vendor_DiscountFilter">
        <sequence>
            <module name="Magento_Catalog"/>
            <module name="Magento_CatalogSearch"/>
            <module name="Magento_Swatches"/>
            <module name="Magento_ConfigurableProduct"/>
            <module name="Magento_Eav"/>
            <module name="Magento_Customer"/>
            <module name="Magento_Store"/>
            <module name="Magento_Backend"/>
            <module name="Magento_MediaStorage"/>
            <module name="Magento_Config"/>
            <module name="Magento_LayeredNavigation"/>
            <module name="Magento_Theme"/>
        </sequence>
    </module>
</config>

3.create the Vendor/DiscountFilter/etc/adminhtml/system.xmlfile

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../Magento/Config/etc/system_file.xsd">
    <system>
        <tab id="discountFilter" translate="label" sortOrder="500">
            <label>Discount Filter</label>
        </tab>
        <section id="discountFiltered" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
            <label>Settings</label>
            <tab>discountFilter</tab>
            <resource>Vendor_DiscountFilter::vendor_discountfilter</resource>
            <group id="discountFilterGroup" translate="label" type="text" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                <label>Discount Filter</label>
                <field id="isEnableDisable" translate="label comment" type="select" sortOrder="10" showInDefault="1" showInWebsite="1" showInStore="1">
                    <label>Enable</label>
                    <source_model>Magento\Config\Model\Config\Source\Yesno</source_model>
                </field>
            </group>
        </section>
    </system>
</config>

4.create Vendor/DiscountFilter/etc/frontend/routes.xml file

<?xml version="1.0" ?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:App/etc/routes.xsd">
    <router id="standard">
        <route frontName="discountfilter" id="discountfilter">
            <module name="Vendor_DiscountFilter"/>
        </route>
    </router>
</config>

5.Create Vendor/DiscountFilter/etc/config.xml file

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:module:Magento_Store:etc/config.xsd">
    <default>
        <discountFiltered>
            <discountFilterGroup>
                <isEnableDisable>1</isEnableDisable>
            </discountFilterGroup>
        </discountFiltered>
    </default>
</config>

6.create Vendor/DiscountFilter/etc/di.xml file

<?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="../../../../../lib/internal/Magento/Framework/ObjectManager/etc/config.xsd">
    <preference for="Magento\Catalog\Model\Layer\FilterList" type="Vendor\DiscountFilter\Model\Layer\FilterList" />
    <type name="Magento\Catalog\Model\Layer\FilterList">
        <plugin name="FilterDiscountList" type="Vendor\DiscountFilter\Model\Layer\FilterList" sortOrder="1" disabled="false"  />
    </type>
</config>

7.create Vendor/DiscountFilter/Model/Layer/Filter/Rating.php file

<?php
namespace Vendor\DiscountFilter\Model\Layer\Filter;

use Magento\Catalog\Model\Layer;
use Magento\Catalog\Model\Layer\Filter\AbstractFilter;
use Magento\Catalog\Model\Layer\Filter\DataProvider\PriceFactory;
use Magento\Catalog\Model\Layer\Filter\Item\DataBuilder;
use Magento\Catalog\Model\Layer\Filter\ItemFactory;
use Magento\Catalog\Model\ResourceModel\Product\CollectionFactory;
use Magento\Framework\App\RequestInterface;
use Magento\Framework\Exception\LocalizedException;
use Magento\Framework\Phrase;
use Magento\Store\Model\StoreManagerInterface;

/**
 * Class Rating
 * @package Vendor\DiscountFilter\Model\Layer\Filter
 */
class Rating extends AbstractFilter
{
    /**
     * @var CollectionFactory
     */
    protected CollectionFactory $productCollectionFactory;
    /**
     * @var PriceFactory
     */
    private $dataProvider;

    /**
     * Rating constructor.
     * @param ItemFactory $filterItemFactory
     * @param StoreManagerInterface $storeManager
     * @param Layer $layer
     * @param DataBuilder $itemDataBuilder
     * @param CollectionFactory $productCollectionFactory
     * @param PriceFactory $dataProviderFactory
     * @param array $data
     * @throws LocalizedException
     */
    public function __construct(
        ItemFactory $filterItemFactory,
        StoreManagerInterface $storeManager,
        Layer $layer,
        DataBuilder $itemDataBuilder,
        CollectionFactory $productCollectionFactory,
        PriceFactory $dataProviderFactory,
        array $data = []
    )
    {
        parent::__construct($filterItemFactory, $storeManager, $layer, $itemDataBuilder, $data);
        $this->productCollectionFactory = $productCollectionFactory;
        $this->_requestVar = 'dis';
        $this->dataProvider = $dataProviderFactory->create(['layer' => $this->getLayer()]);
    }

    /**
     * @return mixed
     */
    public function getResetValue(): mixed
    {
        return $this->dataProvider->getResetValue();
    }

    /**
     * @param RequestInterface $request
     * @return $this|AbstractFilter
     */
    public function apply(RequestInterface $request)
    {
        $filter = $request->getParam($this->getRequestVar());
        if (!$filter || is_array($filter)) {
            return $this;
        }
        $filter = explode('-', $filter);
        list($from, $to) = $filter;
        $entity_id = [];
        $collection = $this->productCollectionFactory->create()
            ->addAttributeToSelect(array('sku', 'price', 'special_price', 'special_to_date', 'special_from_date'))
            ->addAttributeToFilter('special_price', array('notnull' => true));

        foreach ($collection as $product) {
            $price = $product->getPrice();
            if($product->getTypeId() == "bundle")
            {
                $price  = $product->getPriceInfo()->getPrice('regular_price')->getAmount()->getValue() ;
            }
            $sprice = $product->getSpecialPrice();
            $sprice_from_date = $product->getSpecialFromDate();
            $sprice_to_date = $product->getSpecialToDate();
            if ($price > 0 && isset($sprice_from_date) && isset($sprice_to_date) && !empty($sprice_from_date) && !empty($sprice_to_date)) {
                if (time() >= strtotime($sprice_from_date) && time() <= strtotime($sprice_to_date)) {
                    $dis = ($price - $sprice) * 100 / $price;
                    if ($dis >= $from && $dis <= $to) {
                        $entity_id[] = $product->getId();
                    }
                }
            }
        }
        $this->getLayer()
            ->getProductCollection()
            ->addAttributeToFilter('entity_id', array('in' => ($entity_id)));
        return $this;
    }

    /**
     * @return Phrase
     */
    public function getName(): Phrase
    {
        return __('Discount');
    }

    /**
     * @return array
     */
    protected function _getItemsData(): array
    {
        $objectManager = \Magento\Framework\App\ObjectManager::getInstance();;
        $scopeConfig = $objectManager->create('\Magento\Framework\App\Config\ScopeConfigInterface');
        if ($scopeConfig->getValue('discountFiltered/discountFilterGroup/isEnableDisable')) {
            $facets = array(
                '0-20' => '<div class="rating-result"><span>' . __('1% to 20%') . '</span></div>',
                '21-40' => '<div class="rating-result"><span>' . __('21% to 40%') . '</span></div>',
                '41-60' => '<div class="rating-result"><span>' . __('41% to 60%') . '</span></div>',
                '61-80' => '<div class="rating-result"><span>' . __('61% to 80%') . '</span></div>',
                '81-100' => '<div class="rating-result"><span>' . __('81% to 100%') . '</span></div>',
            );
            if (count($facets) > 1) {
                foreach ($facets as $key => $label) {
                    $filter = explode('-', $key);
                    list($from, $to) = $filter;
                    $collection = $this->getLayer()->getCurrentCategory()
                        ->getProductCollection()
                        ->addAttributeToSelect(array('sku', 'price', 'special_price', 'special_to_date', 'special_from_date'))
                        ->addFieldToFilter('special_price', array('gt' => '5'));
                    $count1 = 0;
                    foreach ($collection as $product) {
                        $price = $product->getPrice();
                        if($product->getTypeId() == "bundle")
                        {
                            $price  = $product->getPriceInfo()->getPrice('regular_price')->getAmount()->getValue() ;
                        }
                        $sprice = $product->getSpecialPrice();
                        $sprice_from_date = $product->getSpecialFromDate();
                        $sprice_to_date = $product->getSpecialToDate();
                        if ($price > 0 && isset($sprice_from_date) && isset($sprice_to_date) && !empty($sprice_from_date) && !empty($sprice_to_date)) {
                            if (time() >= strtotime($sprice_from_date) && time() <= strtotime($sprice_to_date)) {
                                $dis = ($price - $sprice) * 100 / $price;
                                if ($dis >= $from && $dis <= $to) {
                                    $count1++;
                                    array($product);
                                }
                            }
                        }
                    }

                    if ($count1 > 0) {
                        $this->itemDataBuilder->addItemData(
                            $label,
                            $key,
                            $count1
                        );
                    }
                }
            }
            return $this->itemDataBuilder->build();
        }
    }

    /**
     * @param $from
     * @param $to
     * @return array
     */
    public function getProduct($from, $to): array
    {
        $sku = [];
        $collection = $this->getLayer()
            ->getProductCollection()
            ->addAttributeToSelect(array('sku', 'price', 'special_price'))
            ->addAttributeToFilter('special_price', array('notnull' => true));
        foreach ($collection as $product) {
            $price = $product->getPrice();
            $sprice = $product->getSpecialPrice();
            $dis = ($price - $sprice) * 100 / $price;
            if ($dis >= $from && $dis <= $to) {
                $sku[] = $product->getId();
            }
        }
        return $sku;
    }
}

8.create Vendor/DiscountFilter/Model/Layer/FilterList.php file

<?php
namespace Vendor\DiscountFilter\Model\Layer;

use Magento\Framework\View\Element\Template\Context;
use Magento\Catalog\Model\Layer;
use Magento\Framework\ObjectManagerInterface;
/**
 * Class FilterList
 * @package Vendor\DiscountFilter\Model\Layer
 */
class FilterList
{
    /**
     * @var ObjectManagerInterface
     */
    private ObjectManagerInterface $objectManager;

    /**
     * FilterList constructor.
     * @param Context $context
     * @param ObjectManagerInterface $objectManager
     */
    public function __construct(
        Context $context,
        ObjectManagerInterface $objectManager
    )
    {
        $this->objectManager = $objectManager;
    }

    /**
     * @param Layer\FilterList $subject
     * @param \Closure $proceed
     * @param Layer $layer
     * @return array|mixed
     */
    public function aroundGetFilters(
        Layer\FilterList $subject,
        \Closure         $proceed,
        Layer            $layer
    )
    {
        $result = $proceed($layer);
        $result[] = $this->objectManager->create('Vendor\DiscountFilter\Model\Layer\Filter\Rating', ['layer' => $layer]);
        return $result;
    }
}

9.create Vendor/DiscountFilter/view/frontend/layout/default.xml file

<?xml version="1.0"?>
<page xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:noNamespaceSchemaLocation="urn:magento:framework:View/Layout/etc/page_configuration.xsd">
    <head>
        <css src="Vendor_DiscountFilter::css/discount-filter.css"/>
    </head>
</page>

10.create Vendor/DiscountFilter/view/frontend/web/css/discount-filter.css

.rating-result{
    display: inline-block;
    margin-top: -5px;
}

• Then set the special price of the product from the "Advance Pricing" and check on frontend side.

NOTE: it's works with a special price only.