drupal: Form API, dynamically hide or show fields based on input

Question

I'm building a form module. One of the early fields is a set of radio buttons. By default the first button is selected. Next I'll have a series of select boxes. One needs to be visible, the others invisible. Then as the user selects a different radio button I want different select boxes to show or hide. How can I hide the field and label by default and show it later dependent upon which radio button (or another select box option for that matter) is chosen?

Staphylorrhaphy

I'm on my mobile so can't find links with ease for you. Check Form API Referenc and you will see a #ajax property to set. That's how we usually do it. But raw JavaScript or jquery is also an option. – Salsbury

Answer 1

You can use the #states property to achieve that. The #states property can be applied to all Form API elements.

Here's the documentation link with an example.

Macguiness

Thanks a lot! I was looking through the api, but there's a lot there so this was easily missed. – Staphylorrhaphy

Really glad it helped :)... -Muhammad. – Macguiness

Here is another documentation link from Lullabot that explains the Drupal Form API States - lullabot.com/articles/form-api-states – Poetics

Answer 2

simple usage example of #states: To show a select field with name 'item' only if another field with name 'type' has value 'sell'

$form['item'] = array( 
        '#title' => t('Task Item'),
        '#type' => 'select',
        '#states' => array(
            // Only show this field when the value of type is sell.
            'visible' => array(
                ':input[name="type"]' => array('value' => 'sell'),
            ),
        ),
    );

Bac

Which hook would this be used in? – Smithy

Answer 3

You could also use 'Conditional Fields' module. Here is the link: https://drupal.org/project/conditional_fields It provides a 'Manage Dependencies' tab while creating a content type where you can select which fields to be visible when a field has a particular value.

Effulgent