QueryFactory.php

1. 9.x drupal/core/lib/Drupal/Core/Entity/Query/QueryFactory.php
2. 9.x drupal/core/modules/field/modules/field_sql_storage/lib/Drupal/field_sql_storage/Entity/QueryFactory.php

<?php

/**
 * @file
 * Definition of Drupal\Core\Entity\Query\QueryFactory.
 */
namespace Drupal\Core\Entity\Query;

use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Factory class Creating entity query objects.
 */
class QueryFactory {

  /**
   * var \Symfony\Component\DependencyInjection\ContainerInterface
   */
  protected $container;

  /**
   * @param \Symfony\Component\DependencyInjection\ContainerInterface $container
   */
  function __construct(ContainerInterface $container) {
    $this->container = $container;
  }

  /**
   * @param string $entity_type
   * @param string $conjunction
   * @return QueryInterface
   */
  public function get($entity_type, $conjunction = 'AND') {
    $service_name = entity_get_controller($entity_type)
      ->getQueryServicename();
    return $this->container
      ->get($service_name)
      ->get($entity_type, $conjunction);
  }

}