zend framework2 - How to add dynamically validators and filters to elements in fieldsets in ZF2? -

i use fieldsets in zf2 forms. can add validators , filters elements:

$form->getinputfilter()->add(array(     'name' => 'element_name',     'required' => true,     'filters' => array(         array('name' => 'zend\filter\stringtrim'),     ),             )); 

but how can if element in fieldset? tried so:

$form->getinputfilter()->add(array(     'fieldset_name' => array(         'name' => 'element_name',         'required' => true,         'filters' => array(             array('name' => 'zend\filter\stringtrim'),         ),        ),                 )); 

but doesn't work

the method of @fouad fodail should preferred. inputspecification should declared @ fieldsetclass itself. if need asked it's simple:

$form->getinputfilter()      ->get('fieldset_name')      ->get('element_name')      ->add($additionalfilter);