如何在列表中按层次顺序显示具有自定义分类法（产品类别）的自定义帖子类型的产品？

我想按以下顺序购买：

h3.parentcategory 1
  -h4.childcategory 1
    -li.product of childcategory 1
    -li.product of childcategory 1
  -h4.childcategory 2
    -li.product of childcategory 2
    -li.product of childcategory 2

h3.parentcategory 2
  -h4.childcategory 1 of parent 2

不幸的是，我不能在第二级（儿童类别1和2）上下功夫。我使用此代码显示类别和产品：

$custom_terms = get_terms( \'productcategory\' );
foreach ( $custom_terms as $custom_term ) {
    wp_reset_query();
    $args = array(  
        \'post_type\' => \'product\',
        \'tax_query\' => array(
            array(
                \'taxonomy\' => \'productcategories\',
                \'field\'    => \'slug\',
                \'terms\'    => $custom_term->slug,
                \'orderby\'  => \'term_group\',
            ),
        ),
    );
    $loop = new WP_Query( $args );
    if ( $loop->have_posts() ) {
        echo \'<h3>\' . $custom_term->name . \'</h2>\';
        while ( $loop->have_posts() ) : $loop->the_post();
            get_the_title();
        endwhile;
    }
}

我需要帮助找出这个列表的嵌套级别。

我编辑这篇文章是为了澄清：感谢大家的帮助。很抱歉我在发帖时是个无赖。。。

我想做的是列出属于子类别的产品，这些子类别可以是一个大家族（Maincategory）的一部分。我试图将子类别归为一个主类别

vegetables (Main)
  -tomatoes (sub)
     -red tomatoe sweet (product)
     -pink tomatoe sour (product)
  -cucumber (sub)
     -some kind of cucumber(product)

fruits (Main)
  -apple(sub)
     -sweet apple (product)
     -Golden delicious (product)

<?php
$parent_terms = get_terms(
    \'name_of_your_taxonomy\',
    array(
        \'parent\' => 0, 
    )
);

foreach ( $parent_terms as $parent_term ) {

    $child_terms = get_terms(
        \'name_of_your_taxonomy\'
        array(
            \'child_of\' => $parent_term->term_id,
        )
    );
    
    foreach ( $child_terms as $child_term ) {
    
        $args = array(
            \'post_type\' => \'product\',
            \'tax_query\' => array(
                array(
                    \'taxonomy\'      => \'name_of_your_taxonomy\',
                    \'field\'         => \'slug\',
                    \'terms\'         => $child_term->slug,
                ),
            ),
        );
    
        $loop = new WP_Query($args);
        
        if ( $loop->have_posts() ) :
        
            while ( $loop->have_posts() ) :
                $loop->the_post();
            
                echo \'<h3>\' . $parent_term->name . \'</h3>\';
                echo \'<h4>\' . $parent_term->name . \'</h4>\';
                echo get_the_title();

            endwhile;
            wp_reset_postdata();
        endif;
    }
}