Import data from arbitrary CSV to WPAlchemy meta fields

Here’s a piece of code similar to what I have used to fix the problem once imported the data:

<?php
define('MY_METABOX_ID', 'my_metabox_id');
define('MY_METABOX_PREFIX', 'my_metabox_prefix_');
define('MY_CUSTOM_POST_TYPE', 'my_custom_post_type');

// Include WordPress
define('WP_USE_THEMES', false);
define('WP_DEBUG', 1);
require_once('../wp-load.php');

// extract all MY_CUSTOM_POST_TYPE posts
$q = new WP_Query('post_type=" . MY_CUSTOM_POST_TYPE . "&nopaging=true');

// for each post
while($q->have_posts()) {
    $q->next_post();

    $p = $q->post;
    $id = $p->ID;

    // check if the field already exists, take action only if it does not
    if (!get_post_meta($id, MY_METABOX_ID . '_fields', true)) {

        // crete the content
        $fields = array(
            MY_METABOX_PREFIX . 'field1',
            MY_METABOX_PREFIX . 'field2',
            MY_METABOX_PREFIX . 'field3',
        );

        //add the meta field
        add_post_meta($id, MY_METABOX_ID . '_fields', $fields);
    }
}
echo 'DONE!';