silverstripe-framework/tests/php/ORM/VersionedOwnershipTest/CustomRelation.php

<?php

namespace SilverStripe\ORM\Tests\VersionedOwnershipTest;

use SilverStripe\Dev\TestOnly;
use SilverStripe\ORM\DataList;
use SilverStripe\ORM\DataObject;
use SilverStripe\ORM\Versioning\Versioned;

/**
 * Object which is owned via a custom PHP method rather than DB relation
 *
 * @mixin Versioned
 */
class CustomRelation extends DataObject implements TestOnly
{
	private static $extensions = array(
		Versioned::class,
	);

	private static $table_name = 'VersionedOwnershipTest_CustomRelation';

	private static $db = array(
		'Title' => 'Varchar(255)',
	);

	private static $owned_by = array(
		'Pages'
	);

	/**
	 * All pages with the same number. E.g. 'Page 1' owns 'Custom 1'
	 *
	 * @return DataList
	 */
	public function Pages()
	{
		$title = str_replace('Custom', 'Page', $this->Title);
		return TestPage::get()->filter('Title', $title);
	}

}