core-bundle/src/Resources/contao/dca/tl_opt_in.php
public function showRelatedRecords($data, $row)
	{
		Contao\System::loadLanguageFile('tl_opt_in_related');
		Contao\Controller::loadDataContainer('tl_opt_in_related');

		$objRelated = $this->Database->prepare("SELECT * FROM tl_opt_in_related WHERE pid=?")
									 ->execute($row['id']);

		while ($objRelated->next())
		{
			$arrAdd = array();
			$arrRow = $objRelated->row();

			foreach ($arrRow as $k=>$v)
			{
				$label = \is_array($GLOBALS['TL_DCA']['tl_opt_in_related']['fields'][$k]['label']) ? $GLOBALS['TL_DCA']['tl_opt_in_related']['fields'][$k]['label'][0] : $GLOBALS['TL_DCA']['tl_opt_in_related']['fields'][$k]['label'];

				$arrAdd[$label] = $v;
			}

			$data['tl_opt_in_related'][] = $arrAdd;
		}

		return $data;
	}
public function showRelatedRecords($data, $row)
	{
		Contao\System::loadLanguageFile('tl_opt_in_related');
		Contao\Controller::loadDataContainer('tl_opt_in_related');

		$objRelated = $this->Database->prepare("SELECT * FROM tl_opt_in_related WHERE pid=?")
									 ->execute($row['id']);

		while ($objRelated->next())
		{
			$arrAdd = array();
			$arrRow = $objRelated->row();

			foreach ($arrRow as $k=>$v)
			{
				$label = \is_array($GLOBALS['TL_DCA']['tl_opt_in_related']['fields'][$k]['label']) ? $GLOBALS['TL_DCA']['tl_opt_in_related']['fields'][$k]['label'][0] : $GLOBALS['TL_DCA']['tl_opt_in_related']['fields'][$k]['label'];

				$arrAdd[$label] = $v;
			}

			$data['tl_opt_in_related'][] = $arrAdd;
		}

		return $data;
	}
Show the related records

@param array $data
@param array $arrRow