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;
    }

}