class VocabularyTranslation

class VocabularyTranslation extends DrupalSqlBase {
  
  /**
   * {@inheritdoc}
   */
  public function query() {
    $query = $this->select('vocabulary', 'v')
      ->fields('v')
      ->fields('i18n', [
      'lid',
      'type',
      'property',
      'objectid',
    ])
      ->fields('lt', [
      'lid',
      'translation',
    ])
      ->condition('i18n.type', 'vocabulary');
    $query->addField('lt', 'language', 'lt.language');
    // The i18n_strings table has two columns containing the object ID, objectid
    // and objectindex. The objectid column is a text field. Therefore, for the
    // join to work in PostgreSQL, use the objectindex field as this is numeric
    // like the vid field.
    $query->join('i18n_strings', 'i18n', '[v].[vid] = [i18n].[objectindex]');
    $query->innerJoin('locales_target', 'lt', '[lt].[lid] = [i18n].[lid]');
    return $query;
  }
  
  /**
   * {@inheritdoc}
   */
  public function fields() {
    return [
      'vid' => $this->t('The vocabulary ID.'),
      'language' => $this->t('Language for this field.'),
      'property' => $this->t('Name of property being translated.'),
      'translation' => $this->t('Translation of either the title or explanation.'),
    ];
  }
  
  /**
   * {@inheritdoc}
   */
  public function prepareRow(Row $row) {
    // For ease of reading the migration use 'language' as the property name for
    // the language.
    $language = $row->getSourceProperty('ltlanguage');
    $row->setSourceProperty('language', $language);
    return parent::prepareRow($row);
  }
  
  /**
   * {@inheritdoc}
   */
  public function getIds() {
    $ids['vid']['type'] = 'integer';
    $ids['language']['type'] = 'string';
    $ids['language']['alias'] = 'lt';
    return $ids;
  }

}