WooCommerce で変数商品を作成し、プログラムで新しい属性値を追加する方法

function create_product_variation($product_id, $variation_data) {
    // Get the parent variable product object
    $product = wc_get_product($product_id);

    $variation_post = array(
        'post_title' => $product->get_name(),
        'post_name' => 'product-' . $product_id . '-variation',
        'post_status' => 'publish',
        'post_parent' => $product_id,
        'post_type' => 'product_variation',
        'guid' => $product->get_permalink()
    );

    // Insert the product variation
    $variation_id = wp_insert_post($variation_post);

    // Create an instance of the variation object
    $variation = new WC_Product_Variation($variation_id);
    ...
}

foreach ($variation_data['attributes'] as $attribute => $term_name) {
    $taxonomy = 'pa_' . $attribute; // The attribute taxonomy

    // Check if the term exists
    if (!term_exists($term_name, $taxonomy)) {
        wp_insert_term($term_name, $taxonomy); // Create the term
    }

    $term_slug = get_term_by('name', $term_name, $taxonomy)->slug; // Get the term slug

    // Set the attribute data in the product variation
    update_post_meta($variation_id, 'attribute_' . $taxonomy, $term_slug);
}

$variation->set_sku($variation_data['sku']);
$variation->set_price($variation_data['regular_price']);
$variation->set_manage_stock(true);
$variation->set_stock_quantity($variation_data['stock_qty']);
...

$variation->save(); 

$parent_id = 123; // Your parent variable product ID

$variation_data_1 = array(
    'attributes' => array(
        'color' => 'Blue',
        'size' => 'Small'
    ),
    'sku' => 'VAR-1234-BLUE-SMALL',
    'regular_price' => '29.99',
    'stock_qty' => 20
);

$variation_data_2 = array(
    'attributes' => array(
        'color' => 'Green',
        'size' => 'Medium'
    ),
    'sku' => 'VAR-1234-GREEN-MEDIUM',
    'regular_price' => '39.99',
    'stock_qty' => 10
);

create_product_variation($parent_id, $variation_data_1);
create_product_variation($parent_id, $variation_data_2);