tos/Resources/migrations/VersionTos20180615080524.php

<?php
namespace Application\Migrations;

use Doctrine\DBAL\Migrations\AbstractMigration;
use Doctrine\DBAL\Schema\Schema;

class VersionTos20180615080524 extends AbstractMigration
{

    public function up(Schema $schema)
    {
        $tos = $schema->getTable('vierbergenlars_tos');

        foreach ($tos->getForeignKeys() as $fk) {
            $tos->removeForeignKey($fk->getName());
            $tos->addForeignKeyConstraint($fk->getForeignTableName(), $fk->getColumns(), $fk->getForeignColumns(), [
                'onDelete' => 'CASCADE'
            ]);
        }
    }

    public function down(Schema $schema)
    {
        $tos = $schema->getTable('vierbergenlars_tos');
        foreach ($tos->getForeignKeys() as $fk) {
            $tos->removeForeignKey($fk->getName());
            $tos->addForeignKeyConstraint($fk->getForeignTableName(), $fk->getColumns(), $fk->getForeignColumns());
        }
    }
}