Migrate Location module content from Drupal 6

To migrate from Location 6.x-3.x to Addressfield 7.x-1.x in Drupal 7 you must create a custom class since the location module data is not stored in CCK. The location and location_instance tables must be manually added by implementing the query method. As of Addressfield 7.x-1.x and Migrate 7.x-2.5 the address subfields (e.g., "field_address:administrative_area") are not available so the location columns must be mapped as arguments to the address field country mapping, and then hidden.

/**
 * Migrate the venue content type.
 */
class VenueMigration extends DrupalNode6Migration {
  public function __construct(array $arguments) {
    parent::__construct($arguments);

    // Map address field
    $address_arguments = array(
      'administrative_area' => array('source_field' => 'province'),
      'locality' => array('source_field' => 'city'),
      'thoroughfare' => array('source_field' => 'street'),
      'premise' => array('source_field' => 'additional'),
      'postal_code' => array('source_field' => 'postal_code'),
    );
    $this->addFieldMapping('field_address', 'country')
         ->arguments($address_arguments);

    // Hide these sources because they are added as arguments
    $unmapped_sources = array(
      'province',
      'city',
      'street',
      'additional',
      'postal_code',
    );
    $this->addUnmigratedSources($unmapped_sources, t('DNM'));
  }

  protected function query() {
    $query = parent::query();

    // Join location table, which is not CCK
    $query->join('location_instance', 'i', 'i.nid = n.nid AND i.vid = n.vid');
    $query->join('location', 'l', 'l.lid = i.lid');
    $query->fields('l', array('street', 'additional', 'city', 'province', 'postal_code', 'country'));

    return $query;
  }

}