DraggableListBuilder.php

<?php

namespace Drupal\Core\Config\Entity;

use Drupal\Core\Entity\DraggableListBuilderTrait;
use Drupal\Core\Entity\EntityInterface;
use Drupal\Core\Entity\EntityStorageInterface;
use Drupal\Core\Entity\EntityTypeInterface;
use Drupal\Core\Form\FormInterface;

/**
 * Defines a class to build a draggable listing of configuration entities.
 */
abstract class DraggableListBuilder extends ConfigEntityListBuilder implements FormInterface {
    use DraggableListBuilderTrait;
    
    /**
     * {@inheritdoc}
     */
    public function __construct(EntityTypeInterface $entity_type, EntityStorageInterface $storage) {
        parent::__construct($entity_type, $storage);
        // Do not inject the form builder for backwards-compatibility.
        $this->formBuilder = \Drupal::formBuilder();
        // Check if the entity type supports weighting.
        if ($this->entityType
            ->hasKey('weight')) {
            $this->weightKey = $this->entityType
                ->getKey('weight');
        }
        $this->limit = FALSE;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function getWeight(EntityInterface $entity) : int|float {
        
        /** @var \Drupal\Core\Config\Entity\ConfigEntityInterface $entity */
        return $entity->get($this->weightKey) ?: 0;
    }
    
    /**
     * {@inheritdoc}
     */
    protected function setWeight(EntityInterface $entity, int|float $weight) : EntityInterface {
        
        /** @var \Drupal\Core\Config\Entity\ConfigEntityInterface $entity */
        $entity->set($this->weightKey, $weight);
        return $entity;
    }

}