EntityReverse.php

<?php

namespace Drupal\views\Plugin\views\relationship;

use Drupal\views\Attribute\ViewsRelationship;
use Drupal\views\Plugin\ViewsHandlerManager;
use Drupal\views\Views;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * A relationship handlers which reverse entity references.
 *
 * @ingroup views_relationship_handlers
 */
class EntityReverse extends RelationshipPluginBase {
    
    /**
     * The views plugin join manager.
     */
    public ViewsHandlerManager $joinManager;
    
    /**
     * The alias for the left table.
     */
    // phpcs:ignore Drupal.NamingConventions.ValidVariableName.LowerCamelName
    public string $first_alias;
    
    /**
     * Constructs an EntityReverse object.
     *
     * @param array $configuration
     *   A configuration array containing information about the plugin instance.
     * @param string $plugin_id
     *   The plugin_id for the plugin instance.
     * @param array $plugin_definition
     *   The plugin implementation definition.
     * @param \Drupal\views\Plugin\ViewsHandlerManager $join_manager
     *   The views plugin join manager.
     */
    public function __construct(array $configuration, $plugin_id, $plugin_definition, ViewsHandlerManager $join_manager) {
        parent::__construct($configuration, $plugin_id, $plugin_definition);
        $this->joinManager = $join_manager;
    }
    
    /**
     * {@inheritdoc}
     */
    public static function create(ContainerInterface $container, array $configuration, $plugin_id, $plugin_definition) {
        return new static($configuration, $plugin_id, $plugin_definition, $container->get('plugin.manager.views.join'));
    }
    
    /**
     * Called to implement a relationship in a query.
     */
    public function query() {
        $this->ensureMyTable();
        // First, relate our base table to the current base table to the
        // field, using the base table's id field to the field's column.
        $views_data = Views::viewsData()->get($this->table);
        $left_field = $views_data['table']['base']['field'];
        $first = [
            'left_table' => $this->tableAlias,
            'left_field' => $left_field,
            'table' => $this->definition['field table'],
            'field' => $this->definition['field field'],
            'adjusted' => TRUE,
        ];
        if (!empty($this->options['required'])) {
            $first['type'] = 'INNER';
        }
        if (!empty($this->definition['join_extra'])) {
            $first['extra'] = $this->definition['join_extra'];
        }
        $first_join = $this->joinManager
            ->createInstance('standard', $first);
        $this->first_alias = $this->query
            ->addTable($this->definition['field table'], $this->relationship, $first_join);
        // Second, relate the field table to the entity specified using
        // the entity id on the field table and the entity's id field.
        $second = [
            'left_table' => $this->first_alias,
            'left_field' => 'entity_id',
            'table' => $this->definition['base'],
            'field' => $this->definition['base field'],
            'adjusted' => TRUE,
        ];
        if (!empty($this->options['required'])) {
            $second['type'] = 'INNER';
        }
        $second_join = $this->joinManager
            ->createInstance('standard', $second);
        $second_join->adjusted = TRUE;
        // use a short alias for this:
        $alias = $this->definition['field_name'] . '_' . $this->table;
        $this->alias = $this->query
            ->addRelationship($alias, $second_join, $this->definition['base'], $this->relationship);
    }

}