<?php

/**
 * Make all fields that were previously eligible for attribute selection on the
 * Add to Cart form continue to use the attribute selection widget.
 */
function commerce_cart_update_7100() {
  // Loop over all the field instances on product bundles.
  foreach (field_info_instances('commerce_product') as $bundle_name => $instances) {
    foreach ($instances as $instance) {
      $field = field_info_field_by_id($instance['field_id']);

      // If the field meets attribute eligibility, it should continue to use the
      // select widget as an attribute field on the Add to Cart form.
      if ($field['cardinality'] == 1 && function_exists($field['module'] . '_options_list')) {
        $instance['commerce_cart_settings'] = array(
          'attribute_field' => TRUE,
          'attribute_widget' => 'select',
        );
      }

      // Save the updated field instance.
      field_update_instance($instance);
    }
  }

  return t('All eligible product attribute fields have been updated to continue using the attribute selection widget.');
}