<?php namespace Aerex\BaikalStorage\Configs; use Symfony\Component\Config\Definition\Builder\TreeBuilder; class Config extends AbstractConfig { protected function getConfigTree() { $treeBuilder = new TreeBuilder('config'); $rootNode = $treeBuilder->getRootNode(); $rootNode->children ->scalarNode('storage') ->isRequired() ->ifNotInArray(['todotxt']) ->thenInvalid('Invalid storage %s') ->end(); return $treeBuilder; } }