gistfile1.php

<?php
function drush_om_timeslot_scheduler_migrate_scheduling_rules($count, $old_field_name, $new_field_name) {
  $watermark = variable_get('om_timeslot_scheduler_rules_migration_watermark', 0);
  $query = db_select('node', 'n');
  $query->fields('n', array());
  $query->condition('type', 'om_timeslot_event', '=');
  $query->range($watermark, $count);
  $resource = $query->execute();
  $updates_performed = FALSE;
  $map = drush_om_timeslot_scheduler_scheduling_rule_map();
  while ($row = $resource->fetchObject()) {
    $node = node_load($row->nid);
    $l = $node->language;
    if (!empty($node->{$old_field_name}[$l][0]['value'])) {
      $new_value = $map[$node->{$old_field_name}[$l][0]['value']];
      $node->{$new_field_name} = array($l => array(array('value' => $new_value)));
      node_save($node);
      $updates_performed = TRUE;
    }
  }
  if ($updates_performed == TRUE) {
    variable_set('om_timeslot_scheduler_rules_migration_watermark', $watermark + $count);
  }
  else {
    variable_set('om_timeslot_scheduler_rules_migration_watermark', 0);
  }
}

function drush_om_timeslot_scheduler_scheduling_rule_map() {
  return array(
    'fewest_aired_shows_scheduling_rule' => 'Drupal\om_timeslot_scheduler\Scheduling\Rules\SchedulingRuleLeastAiredContent',
    'least_aired_shows_with_language_scheduling_rule' => 'Drupal\om_timeslot_scheduler\Scheduling\Rules\SchedulingRuleLeastAiredContent',
    'highest_bayesian_average_rule' => 'Drupal\om_timeslot_scheduler\Scheduling\Rules\SchedulingRuleHighestRatedContent',
    'least_aired_show_in_project_scheduling_rule' => 'Drupal\om_timeslot_scheduler\Scheduling\Rules\SchedulingRuleLeastAiredContentProject',
    'locally_produced_shows_scheduling_rule' => 'Drupal\om_timeslot_scheduler\Scheduling\Rules\SchedulingRuleNewestLocalContent',
    'newest_episode_in_project_scheduling_rule' => 'Drupal\om_timeslot_scheduler\Scheduling\Rules\SchedulingRuleNewestContentProject',
  );
}