D6->D7 migration

news_migrate.migrate.inc

<?php

/**
 * Implements hook_migrate_api().
 */
function news_migrate_migrate_api() {
  /**
   * Declare the api version and migration group.
   */
  $api = array(
    'api' => 2,
    'groups' => array(
      'News' => array(
        'title' => t('News'),
      ),
    ),
    'migrations' => array(
      'Article' => array(
        'description' => t('Migration of articles from Drupal 6'),
        'class_name' => 'NewsArticleMigration',
        'group_name' => 'News',
        'source_type' => 'article',
        'destination_type' => 'archive_article',
        'source_connection' => 'legacy',
        'source_version' => 6,
        'format_mappings' => array(3 => 'filtered_html'),
      ),
      'Taxonomy' => array(
        'class_name' => 'NewsTermMigration',
        'description' => t('Migration of Topics terms from Drupal 6'),
        'group_name' => 'News',
        'source_vocabulary' => '1',  // D6 Vocabulary ID
        'destination_vocabulary' => 'archive_topics',
        'source_connection' => 'legacy',
        'source_version' => 6,
      ),
      'User' => array(
        'description' => t('Migration of users from Drupal 6'),
        'class_name' => 'DrupalUser6Migration',
        'group_name' => 'News',
        'source_connection' => 'legacy',
        'source_version' => 6,
      )
    ),
  );

  return $api;
}

node.inc

<?php

/**
 * Common mappings for the Drupal 6 node migrations.
 */

class NewsArticleMigration extends DrupalNode6Migration {
  public function __construct(array $arguments) {
    // Add any other data we're pulling into the source row, before the parent
    // constructor.

    parent::__construct($arguments);

    $this->addFieldMapping('field_link_to_external_story', 'field_external_link');
    $this->addFieldMapping('field_alternate_title','field_secondary_title');
    $this->addFieldMapping('field_archive_topics', '1')
      ->sourceMigration('Taxonomy');
    $this->addFieldMapping('field_archive_topics:source_type')
      ->defaultValue('tid');
  }
  
  /**
   * Implements Migration::prepareRow().
   */
  public function prepareRow($row) {
    drush_print_r($row);
  }
  
}