gistfile1.txt

function asin_field_views_data($field) {
  $data = field_views_field_default_views_data($field);

  // Skip items that are already in the views data.
  $field_skips = array_keys($data);
  array_unshift($field_skips, 'table', 'entity_id', 'revision_id');

  foreach ($data as $table_name => $table_data) {
    foreach ($table_data as $field_name => $field_data) {
      if (!in_array($field_name, $field_skips)) {
        $data[$table_name][$field_name]['relationship'] = array(
          'handler' => 'views_handler_relationship',
          'base' => 'amazon_item',
          'base_field' => 'asin',
          'label' => t('ASIN from !field_name', array('!field_name' => $field['field_name'])),
        );
        debug($data[$table_name][$field_name]['relationship'], "\$data[$table_name][$field_name]['relationship']");
      }
    }
  }
  return $data;
}