ResponsiveImageStyles.php

<?php

namespace Drupal\responsive_image\Plugin\migrate\source\d7;

use Drupal\migrate\Row;
use Drupal\migrate_drupal\Plugin\migrate\source\DrupalSqlBase;

/**
 * Gets Drupal responsive image styles source from database.
 *
 * Breakpoints are YAML files in Drupal 8. If you have a custom
 * theme and want to migrate its responsive image styles to
 * Drupal 8, create the respective your_theme.breakpoints.yml file at
 * the root of the theme.
 *
 * @see https://www.drupal.org/docs/8/theming-drupal-8/working-with-breakpoints-in-drupal-8
 *
 * @MigrateSource(
 *   id = "d7_responsive_image_styles",
 *   source_module = "picture"
 * )
 */
class ResponsiveImageStyles extends DrupalSqlBase {
    
    /**
     * {@inheritdoc}
     */
    public function query() {
        return $this->select('picture_mapping', 'p')
            ->fields('p');
    }
    
    /**
     * {@inheritdoc}
     */
    public function fields() {
        $fields = [
            'label' => $this->t('The human-readable name of the mapping'),
            'machine_name' => $this->t('The machine name of the mapping'),
            'breakpoint_group' => $this->t('The group this mapping belongs to'),
            'mapping' => $this->t('The mappings linked to the breakpoints group'),
        ];
        return $fields;
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIds() {
        $ids['machine_name']['type'] = 'string';
        return $ids;
    }
    
    /**
     * {@inheritdoc}
     */
    public function prepareRow(Row $row) {
        $row->setSourceProperty('mapping', unserialize($row->getSourceProperty('mapping')));
        return parent::prepareRow($row);
    }

}