ProfileFieldTranslation.php

<?php

namespace Drupal\config_translation\Plugin\migrate\source\d6;

use Drupal\user\Plugin\migrate\source\ProfileField;
// cspell:ignore nprofile objectid

/**
 * Drupal 6 i18n strings profile field source from database.
 *
 * For available configuration keys, refer to the parent classes.
 *
 * @see \Drupal\migrate\Plugin\migrate\source\SqlBase
 * @see \Drupal\migrate\Plugin\migrate\source\SourcePluginBase
 *
 * @MigrateSource(
 *   id = "d6_profile_field_translation",
 *   source_module = "i18nprofile"
 * )
 */
class ProfileFieldTranslation extends ProfileField {
  
  /**
   * {@inheritdoc}
   */
  public function query() {
    $query = parent::query();
    $query->fields('i18n', [
      'property',
    ])
      ->fields('lt', [
      'lid',
      'translation',
      'language',
    ]);
    $query->leftJoin('i18n_strings', 'i18n', '[i18n].[objectid] = [pf].[name]');
    $query->innerJoin('locales_target', 'lt', '[lt].[lid] = [i18n].[lid]');
    return $query;
  }
  
  /**
   * {@inheritdoc}
   */
  public function fields() {
    $fields = [
      'lid' => $this->t('Locales target language ID.'),
      'language' => $this->t('Language for this field.'),
      'translation' => $this->t('Translation of either the title or explanation.'),
    ];
    return parent::fields() + $fields;
  }
  
  /**
   * {@inheritdoc}
   */
  public function getIds() {
    $ids['language']['type'] = 'string';
    $ids['lid']['type'] = 'integer';
    $ids['lid']['alias'] = 'lt';
    return parent::getIds() + $ids;
  }

}