Проверка и преобразование/создание вариативного товара в WooCommerce.

woocommerce.php

if ( ! function_exists( 'create_gift_variation' ) ) {
    function create_gift_variation( $product_id, $price ) {
        $product_variation = get_posts(
            array(
                'post_parent' => $product_id,
                'post_title' => 'wfg_gift_product',
                'post_type' => 'product_variation',
                'posts_per_page' => 1
            )
         );

        if( !empty($product_variation) ) {
            update_post_meta( $product_variation[0]->ID, '_price', $price);
            update_post_meta( $product_variation[0]->ID, '_regular_price', $price);
            update_post_meta( $product_variation[0]->ID, '_wfg_gift_product', 1);

            return $product_variation[0]->ID;
        }

        $admin = get_users( 'orderby=nicename&role=administrator&number=1' );
        $variation = array(
            'post_author' => $admin[0]->ID,
            'post_status' => 'publish',
            'post_name' => 'product-' . $product_id . '-variation',
            'post_parent' => $product_id,
            'post_title' => 'wfg_gift_product',
            'post_type' => 'product_variation',
            'comment_status' => 'closed',
            'ping_status' => 'closed'
        );

        $post_id = wp_insert_post( $variation );
        update_post_meta( $post_id, '_price', $price);
        update_post_meta( $post_id, '_regular_price', $price);
        update_post_meta( $post_id, '_wfg_gift_product', 1);

        return $post_id;
    }
}