Magento2.4.2: How to sort product by custom price attribute?

Question

I want to sort product collection by Custom Price attribute. here is my code

Here is my code, what is the problem here, i dont understand?

<?php
namespace Vendor\Module\Model\VisualMerchandiser\Sorting;
use Magento\Catalog\Model\ResourceModel\Product\Collection;
use Magento\VisualMerchandiser\Model\Sorting\SortAbstract;
use Magento\VisualMerchandiser\Model\Sorting\SortInterface;
class CustomPriceBottom extends SortAbstract implements SortInterface
{
    /**
     * @param Collection $collection
     * @return Collection
     */
    public function sort(
        Collection $collection
    ): Collection {
        $collection->addAttributeToSelect('*')
            ->setOrder('custom_price', 'DESC');
        
//        $collection->getSelect()
//            ->distinct('entity_id')
//            ->reset(Zend_Db_Select::ORDER)
//            ->order('custom_price ' . CollectionAlias::SORT_ORDER_ASC);
        return $collection;
    }
    /**
     * @return string
     */
    public function getLabel(): string
    {
        return __("Custom Price Bottom");
    }
}

Answer 1

You didn't reset collection order before apply your custom order

In your case you can extends from \Magento\VisualMerchandiser\Model\Sorting\AttributeAbstract and implements getSortField, getSortDirection and getLabel

You can see as example \Magento\VisualMerchandiser\Model\Sorting\Name\Descending

Answer 2

<?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */

namespace Vendor\Module\Model\VisualMerchandiser\Sorting;

use Magento\VisualMerchandiser\Model\Sorting\AttributeAbstract;

class CustomPriceBottom extends AttributeAbstract
{
    /**
     * @return string
     */
    public function getLabel(): string
    {
        return __("Custom Price Bottom");
    }

    /**
     * @return string
     */
    protected function getSortField(): string
    {
        return 'custom_price';
    }

    /**
     * @return string
     */
    protected function getSortDirection(): string
    {
        return $this->descOrder();
    }
}