Snippet Snack: Create Display Suite fields for Flag & Flag Count

/**
 * Implements hook_ds_fields_info().
 */
function yourmodule_ds_fields_info($entity_type) { 
  $fields = array();
 
  if ($flags = flag_get_flags($entity_type)) {
    // Build flag options.
    foreach ($flags as $name => $flag) {
      $fields['flag_' . $name] = array(
        'title' => t('Flag - @flag_title', array('@flag_title' => $flag->title)),
        'field_type' => DS_FIELD_TYPE_FUNCTION,
        'function' => 'yourmodule_ds_field_flag',
        'properties' => array('flag' => $flag),
      );
      $fields['flag_count_' . $name] = array(
        'title' => t('Flag Count - @flag_title', array('@flag_title' => $flag->flag_short)),
        'field_type' => DS_FIELD_TYPE_FUNCTION,
        'function' => 'yourmodule_ds_field_flag_count',
        'properties' => array(
          'flag' => $flag,
        ),
      );
    }
  }
 
  return array('node' => $fields);
}
/**
 * Generate flag link for Display Suite.
 */
function yourmodule_ds_field_flag($field) {
  $entity = $field['entity'];
  $flag = $field['properties']['flag'];
  return flag_create_link($flag->name, $entity->nid);
}
 
/**
 * Generate flag count for Display Suite.
 */
function yourmodule_ds_field_flag_count($field) {
  $entity = $field['entity'];
  $flag = $field['properties']['flag'];
 
  // We are electing not to use flag_get_counts() because it is not flag specific.
  $query = db_select('flag_counts' ,'fc');
  $query->fields('fc', array('count'));
  $query->condition('fc.fid', $flag->fid);
  $query->condition('fc.content_type', 'node');
  $query->condition('fc.content_id', $entity->nid);
  $count = $query->execute()->fetchColumn();
 
  return !empty($count) ? $count : 0;
}