Empty fields

This module provides a way to show empty fields that would otherwise be hidden. It achieves this by appending new settings to existing display formatters. These settings allow you to display a value using either:

• custom text, as defined by the field administrator;
• to show the results of a custom callback;
• or, to show the default empty value (if default is not empty itself).

This last option may be useful in case the field is not required and the instance default value was added after content had been already created.

For example, you could have a list of checkboxes. If none are checked, normally the entire field would be removed from the display. However, with this module you could display something like "Status unknown", "Nothing selected" or "This user failed their IQ test" when the field was empty.

Note that this can be achieved in a custom preprocess callback or hook_field_attach_view_alter() if you know some PHP coding, but this module makes it configurable in the user interface.

Installation

1. Install this module using the official Backdrop CMS instructions at https://backdropcms.org/guide/modules.

Configuration

The module can be configured on each content type's display formatter.

API

For specific use-cases, you can define a custom callback to generate dynamic content.

First, implement hook_empty_fields(). This returns an array indexed by the class name that implements the handler.

/**
 * Implements hook_empty_fields().
 */
function HOOK_empty_fields() {
  $items = array(
    'CurrentTimeEmptyFieldText' => array(
      'title' => t('Display current time if empty'),
    ),
  );
  return $items;
}

Create a new concrete class that extends the abstract class EmptyFieldHandler.

/**
 * @file
 * Contains the CurrentTimeEmptyFieldText plugin for EmptyFieldHandler.
 */

/**
 * Defines CurrentTimeEmptyFieldText class.
 */
class CurrentTimeEmptyFieldText extends EmptyFieldHandler {

  /**
   * Implementation of EmptyFieldText::react().
   */
  public function react($context) {
    return format_date(time());
  }

  /**
   * Implementation of EmptyFieldText:summaryText().
   */
  public function summaryText() {
    return t('Empty Text: current time');
  }

}

Register this class in your module:

/**
 * Implements hook_autoload_info().
 */
function YOUR_MODULE_autoload_info() {
  return array(
    'CurrentTimeEmptyFieldText' => 'plugins/empty_fields_handler_current_time.inc',
  );
}

The context has the entity_type, entity, view_mode as well as the empty field details, field and instance.

If the callback is empty or a zero-length string, the empty field will not be rendered.

License

This project is GPL v2 software. See the LICENSE.txt file in this directory for complete text.

Maintainers

• Herb v/d Dool

Credits

Ported to Backdrop by Herb v/d Dool.

Drupal version currently maintained by:

• Alan D.
• rypit
• andypost