Allow array (with default value) or null in Symfony 2.1 semantic configuration
You could try something like:
$node->arrayNode('foo') ->beforeNormalization() ->ifTrue(function($v) { return $v === null; }) ->then(function($v) { return array(); }) ->end() ->prototype('scalar')->end() ->defaultValue(array('1', '2', '3')) ->end();Or maybe the even simplier:
$node->arrayNode('foo') ->treatNullLike(array()) ->prototype('scalar')->end() ->defaultValue(array('1', '2', '3')) ->end();Otherwise you can use the variableNode rather than the arrayNode; this will give you more freedom but less validation/merging logic out of the box.