function hook_field_settings_form

Add settings to a field settings form.

Invoked from field_ui_field_settings_form() to allow the module defining the field to add global settings (i.e. settings that do not depend on the bundle or instance) to the field settings form. If the field already has data, only include settings that are safe to change.

@todo: Only the field type module knows which settings will affect the field's schema, but only the field storage module knows what schema changes are permitted once a field already has data. Probably we need an easy way for a field type module to ask whether an update to a new schema will be allowed without having to build up a fake $prior_field structure for hook_field_update_forbid().

Parameters

$field: The field structure being configured.

$instance: The instance structure being configured.

$has_data: TRUE if the field already has data, FALSE if not.

Return value

The form definition for the field settings.

Related topics

File

drupal/modules/field_ui/field_ui.api.php, line 38

Hooks provided by the Field UI module.

Code

function hook_field_settings_form($field, $instance, $has_data) {
  $settings = $field['settings'];
  $form['max_length'] = array(
    '#type' => 'textfield',
    '#title' => t('Maximum length'),
    '#default_value' => $settings['max_length'],
    '#required' => FALSE,
    '#element_validate' => array(
      'element_validate_integer_positive',
    ),
    '#description' => t('The maximum length of the field in characters. Leave blank for an unlimited size.'),
  );
  return $form;
}