The following is a snippet on how to enable fields to appear and/or disappear based on the state of other fields.
<?php
/**
* Modifications for including State API functionalities. The idea is to hide the fields field_referme_industry
* and field_referme_major_skills, based on the value of another field.
* The functionality can be implemented during the after_build phase
*/
function jc_form_alter(&$form, &$form_state, $form_id) {
//drupal_set_message("Form Id is: $form_id ");
if($form_id == 'referme_node_form') {
$form['field_referme_industry']['#after_build'] = array('jc_referme_ctc_after_build');
$form['field_referme_major_skills']['#after_build'] = array('jc_referme_ctc_after_build');
}
}
/**
* Hide the industry and Major Skills when CTC is mentioned as Fresher
*/
function jc_referme_ctc_after_build($form_entity, &$form_state) {
$form_entity['#states'] = array(
'invisible' => array(
':input[name="field_referme_current_ctc[und]"]' => array('value' => t('Fresher')),
),
);
return $form_entity;
}
?>
States API also allows providing multiple values for triggering
<?php
'#states' => array(
'visible' => array(
':input[name="field_star_rating"]' => array(
array('value' => t('5')),
array('value' => t('4'))
),
),
),
?>
--
https://api.drupal.org/api/drupal/includes%21common.inc/function/drupal_process_states/7
http://evolvingweb.ca/story/extending-form-api-states-regular-expressions