在WooCommerce的wc_get_products中获取自定义分类brand_heirarchy关联ID

我通过init动作注册了自定义分类brand_heirarchy，代码如下：

add_action( 'init', 'product_brand_order_taxonomy' );
function product_brand_order_taxonomy()  {
    $labels = array(
        'name'                       => 'Brand Heirarchy',
        'singular_name'              => 'Brand Heirarchy',
        'menu_name'                  => 'Brand Heirarchy',
        'all_items'                  => 'All Brand Heirarchies',
        'parent_item'                => 'Parent Brand Heirarchy',
        'parent_item_colon'          => 'Parent Brand Heirarchy:',
        'new_item_name'              => 'New Brand Heirarchy Name',
        'add_new_item'               => 'Add New Brand Heirarchy',
        'edit_item'                  => 'Edit Brand Heirarchy',
        'update_item'                => 'Update Brand Heirarchy',
        'separate_items_with_commas' => 'Separate Brand Heirarchy with commas',
        'search_items'               => 'Search Brand Heirarchies',
        'add_or_remove_items'        => 'Add or remove Brand Heirarchies',
        'choose_from_most_used'      => 'Choose from the most used Brand Heirarchies',
    );
    $args = array(
        'labels'                     => $labels,
        'hierarchical'               => true,
        'public'                     => true,
        'show_ui'                    => true,
        'show_admin_column'          => true,
        'show_in_nav_menus'          => true,
        'show_tagcloud'              => true,
    );
    register_taxonomy( 'brand_heirarchy', 'product', $args );
    register_taxonomy_for_object_type( 'brand_heirarchy', 'product' );
}

现在使用wc_get_products获取产品时，希望返回结果中包含产品关联的brand_heirarchy分类ID，当前获取代码如下：

$product_args = array(
    'post_status' => 'publish',
    'limit' => -1,
    'category' => $parent_brand_slugs
);

$products = wc_get_products($product_args);

目前返回的产品对象仅包含category_ids，但我需要同时获取关联的brand_heirarchy分类ID。已知WooCommerce原生不支持该功能，尝试过woocommerce_product_object_query_args过滤器但未成功，不想用循环调用wp_get_object_terms这种低效方式，求更高效的实现方法。

以下两种方法都能避免循环查询的性能损耗，一次性获取所需分类ID：

方法一：通过查询子句关联分类表 #

直接修改WooCommerce产品查询的SQL语句，关联分类关系表，把brand_heirarchy的ID拼接后附加到产品对象上：

add_filter( 'woocommerce_product_query_post_clauses', 'attach_brand_hierarchy_ids', 10, 2 );
function attach_brand_hierarchy_ids( $clauses, $query ) {
    global $wpdb;

    // 仅针对产品类型的查询生效
    if ( isset( $query->query_vars['post_type'] ) && $query->query_vars['post_type'] === 'product' ) {
        // 关联term关系表和分类表
        $clauses['join'] .= " LEFT JOIN {$wpdb->term_relationships} tr ON {$wpdb->posts}.ID = tr.object_id";
        $clauses['join'] .= " LEFT JOIN {$wpdb->term_taxonomy} tt ON tr.term_taxonomy_id = tt.term_taxonomy_id AND tt.taxonomy = 'brand_heirarchy'";
        
        // 按产品ID分组，避免重复结果
        $clauses['groupby'] = "{$wpdb->posts}.ID";
        
        // 用GROUP_CONCAT拼接多个分类ID（支持产品关联多个分类的场景）
        $clauses['fields'] .= ", GROUP_CONCAT(tt.term_id SEPARATOR ',') AS brand_hierarchy_ids";
    }

    return $clauses;
}

add_action( 'woocommerce_product_query_posts_found', 'map_brand_ids_to_product', 10, 2 );
function map_brand_ids_to_product( $products, $query ) {
    if ( empty( $products ) ) return $products;

    foreach ( $products as $product ) {
        if ( isset( $product->brand_hierarchy_ids ) ) {
            // 把拼接的字符串转为ID数组，过滤空值
            $brand_ids = array_filter( explode( ',', $product->brand_hierarchy_ids ) );
            $product->brand_hierarchy_ids = $brand_ids;
        }
    }

    return $products;
}

使用时无需修改原有查询代码，获取到的$products对象会直接带有brand_hierarchy_ids属性，值为分类ID数组。

方法二：扩展产品查询参数 #

添加自定义查询参数，让wc_get_products支持按需返回brand_heirarchy分类ID：

add_filter( 'woocommerce_product_query_args', 'add_brand_hierarchy_support', 10, 2 );
function add_brand_hierarchy_support( $args, $query ) {
    // 当查询参数中包含include_brand_hierarchy时，执行关联查询
    if ( $query->get('include_brand_hierarchy') ) {
        global $wpdb;
        $args['fields'] = "{$wpdb->posts}.*, GROUP_CONCAT(tt.term_id SEPARATOR ',') AS brand_hierarchy_ids";
        $args['join'] .= " LEFT JOIN {$wpdb->term_relationships} tr ON {$wpdb->posts}.ID = tr.object_id";
        $args['join'] .= " LEFT JOIN {$wpdb->term_taxonomy} tt ON tr.term_taxonomy_id = tt.term_taxonomy_id AND tt.taxonomy = 'brand_heirarchy'";
        $args['groupby'] = "{$wpdb->posts}.ID";
    }
    return $args;
}

add_filter( 'woocommerce_product_object_query_result', 'assign_brand_ids_to_product', 10, 2 );
function assign_brand_ids_to_product( $product, $post ) {
    if ( isset( $post->brand_hierarchy_ids ) ) {
        $brand_ids = array_filter( explode( ',', $post->brand_hierarchy_ids ) );
        $product->brand_hierarchy_ids = $brand_ids;
    }
    return $product;
}

然后修改产品查询代码，添加自定义参数：

$product_args = array(
    'post_status' => 'publish',
    'limit' => -1,
    'category' => $parent_brand_slugs,
    'include_brand_hierarchy' => true // 新增参数，触发分类ID查询
);

$products = wc_get_products($product_args);

获取到的每个产品对象都会带有brand_hierarchy_ids属性，包含关联的分类ID数组。

内容的提问来源于stack exchange，提问作者Senica Gonzalez