How to alter a form element to include it inside a fieldset

Question

I am using field_attach_form() to display an entity's form. When I call this function, it automatically builds the form, which does not contain any fieldsets, just ungrouped form elements.

Before the form is displayed I would like to take some of the form elements and group them into fieldsets. If I have something like this:

$form array:
    form element 1
        attributes
    form element 2
        attributes
    fieldset1
        attributes
    fieldset2
        attributes

Is there a form element attribute or special function that will allow me to tell Drupal to automatically place "form element 1" into "fieldset1"?

Alternatively, can this be done at the core/entity level, not the custom module, so that when field_attach_form() is called the fieldsets are automatically created?

Answer 1

You can use $form['#pre_render'][] = 'yourfunction'; and move the fields to the fieldset in this function.

Answer 2

This code might help you out.

   $form['date_fieldset'] = array(
        '#type' => 'fieldset',
        '#title' => t('Select Start and End dates'),
        '#collapsible' => TRUE,
//        '#tree' => TRUE,
    );

    $form['date_fieldset']['date_inactive_start'] = array(
        '#title' => t('Start date'),
        '#type' => 'date_popup', // Provided by the date_popup module
        '#date_format' => 'd/m/Y',
        '#date_year_range' => '0:+1',
        '#required' => TRUE,
        '#size' => 8,
        '#default_value' => date('Y-m-d', time()), // Default value must be in 'Y-m-d' format.
    );

    $form['date_fieldset']['date_inactive_end'] = array(
        '#title' => t('End date'),
        '#type' => 'date_popup', // Provided by the date_popup module
        '#date_format' => 'd/m/Y',
        '#date_year_range' => '0:+2',
        '#required' => TRUE,
        '#size' => 8,
        '#default_value' => date('Y-m-d', time()), // Default value must be in 'Y-m-d' format.
    );

Answer 3

If someone is looking for a complete example on how to do this:

// hook_form_BASE_FORM_ID_alter to target only article node edit forms
function my_module_form_article_node_form_alter(&$form, &$form_state, $form_id) {

    $form['#pre_render'][] = 'add_to_fieldset';

}

function add_to_fieldset($form) {
    // Adding element to the publishing options fieldset on node form

    $form['options']['element_to_add'] = $form['element_to_add'];
    unset($form['element_to_add']);

    return $form;

}