BlockCustom.php

<?php

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

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

/**
 * Drupal 7 custom block source from database.
 *
 * @MigrateSource(
 *   id = "d7_block_custom",
 *   source_module = "block"
 * )
 */
class BlockCustom extends DrupalSqlBase {
    
    /**
     * {@inheritdoc}
     */
    public function query() {
        return $this->select('block_custom', 'b')
            ->fields('b');
    }
    
    /**
     * {@inheritdoc}
     */
    public function fields() {
        return [
            'bid' => $this->t('The numeric identifier of the block/box'),
            'body' => $this->t('The block/box content'),
            'info' => $this->t('Admin title of the block/box.'),
            'format' => $this->t('Input format of the custom block/box content.'),
        ];
    }
    
    /**
     * {@inheritdoc}
     */
    public function getIds() {
        $ids['bid']['type'] = 'integer';
        return $ids;
    }

}