虽然Maugly的方法看起来更具可读性，但在数组上运行3次循环对我来说并不合适。所以这里是另一种方法，它可能对某些人来说可读性较差，但在不运行循环3次的情况下也可以工作。

function print_taxonomy_ranks( $terms ) {
    // if terms is not array or its empty don\'t proceed
    if ( ! is_array( $terms ) || empty( $terms ) ) {
        return false;
    }

    foreach ( $terms as $term ) {
        // if the term have a parent, set the child term as attribute in parent term
        if ( $term->parent != 0 )  {
            $terms[$term->parent]->child = $term;   
        } else {
            // record the parent term
            $parent = $term;
        }
    }

    echo "Order: $parent->name, Family: {$parent->child->name}, Sub-Family: {$parent->child->child->name}";
}

我遇到过这样的情况，一篇文章可以标记为多个类别组，以及父类别中的多个子类别，因此我希望我的层次结构能够反映这一点。我还想要几行代码：

$terms = get_the_terms($id, \'department_categories\');
foreach($terms as $key => $term){
    if($term->parent != 0){
        $terms[$term->parent]->children[] = $term;
        unset($terms[$key]);
    }
}

希望其他人觉得这很有用，以防他们只是在寻找一些逻辑指导，而不是“插件”！

这个话题有点老了，但我认为仍然相关，因为它仍然是一个完全痛苦的话题。

我使用这个递归函数，它接受两个数组作为引用。它将创建一个结构如下的数组：[term_id] => term_object->children->child_terms_array->children->child_terms_array.

<?php
function sort_terms_hierarchically( array &$terms, array &$into, $parent_id = 0 ) {
    foreach ( $terms as $i => $term ) {
        if ( $term->parent == $parent_id ) {
            $into[$term->term_id] = $term;
            unset( $terms[ $i ] );
        }
    }

    foreach ( $into as $top_term ) {
        $top_term->children = array();
        $this->sort_terms_hierarchically( $terms, $top_term->children, $top_term->term_id );
    }

}

$terms = get_the_terms( \'taxslug\', $post );
$sorted_terms = array();
sort_terms_hierarchically( $terms, $sorted_terms );

// Will log the nested arrays of term objects.
error_log( print_r( $sorted_terms, true ) );

灵感来自Michal Mau answer 和Manny Fleurmond answer 这是我的解决方案：我和@Lucas Bustamante有同样的问题：如果帖子有两个父类别呢？

我的解决方案是创建另一个对象数组，比较term_id 并检查parent 钥匙

function print_taxonomic_ranks( $terms ){

    if ( ! is_array( $terms ) || empty( $terms ) ) {
        return false;
    }

    $parent_terms = array();

    // get only parents
    foreach ( $terms as $term ) {
        if ($term->parent === 0) {
            $term->child = Array();
            $parent_terms[] = $term;
        }
    }

    // compare and nested
    foreach ( $terms as $term ) {
        if ($term->parent != 0) {
            foreach ($parent_terms as $key => $value) {
                if ($term->parent === $value->term_id) {
                    $parent_terms[$key]->child[] = $term;
                }
            }
        }
    }

    // output results
    foreach ( $parent_terms as $term ) {

        //parent term
        echo \'<span class="d-block">\'.$term->name.\'\';

        if ($term->child) {
            $i = 1;
            foreach ( $term->child as $child ) {
                //echo \'<span class="text-danger">\'.$i.\'</span>\';
                echo ($i <= 1)? ": " : "";
                echo \'<span class="font-weight-normal">\'.$child->name.\'</span>\';
                echo ($i < count($term->child))? ", " : "";
            $i++;                
            }          
        }
        echo \'.<span>\';
    }
}

谢谢Maugly，

这是我修改过的代码版本，如果有人需要，它包含了术语permalinks

function print_show_location( $terms = \'\' ){

// check input
if ( empty( $terms ) || is_wp_error( $terms ) || ! is_array( $terms ) )
    return;

// set id variables to 0 for easy check 
$country_id = $state_id = $city_id = 0;

// get country
foreach ( $terms as $term ) {
    if ( $country_id || $term->parent )
        continue;
    $country_id  = $term->term_id;
    $country_slug = $term->slug;
    $country = \'<a href="\'.get_term_link($country_slug, \'location\').\'">\'.$term->name.\'</a>\';
}

// get state
foreach ( $terms as $term ) { 
    if ( $state_id || $country_id != $term->parent )
        continue;
    $state_id = $term->term_id;
    $state_slug = $term->slug;
    $state = \'<a href="\'.get_term_link($state_slug, \'location\').\'">\'.$term->name.\'</a>\';
}

// get city
foreach ( $terms as $term ) { 
    if ( $city_id || $state_id != $term->parent ) 
        continue;
    $city_id = $term->term_id;
    $city_slug = $term->slug;
    $city = \'<a href="\'.get_term_link($city_slug, \'location\').\'">\'.$term->name.\'</a>\';
}

// output
echo "$city, $state - $country";

}

根据需要，我使用了几个递归函数。两者都需要术语列表、起始父id和起始（通常为空）数组来放置结果列表。

第一版

$terms = [a list of terms objects, use get_terms of whatever]
$ordered_terms = array(); // here you\'ll find your ordered terms, from root to final child

function list_terms_by_parent($parent_id = 0, &$terms, &$ordered_terms){
  $root_parent = $parent_id;

  foreach($terms as $index => $term){
    if($term->parent == (int) $parent_id){
      $ordered_terms[$term->term_id] = $term;
      $root_parent = $term->term_id;
      unset($terms[$index]);
    }
  }

  if(!empty($terms)) list_terms_by_parent($root_parent, $terms, $ordered_terms);
}

$term_ids = [should be a list of ids in the form of child_id => parent_id]

// a fast way to get that kind of list is to use WP_Term_query, example:
//$terms_query = new WP_Term_Query(array(
//  \'taxonomy\' => \'product_categories\'
//  ,\'object_ids\' => $post->ID
//  ,\'hide_empty\' => false
//  ,\'fields\' => \'id=>parent\'
//));


$ordered_terms = array(); // here you\'ll find your ordered terms, from root to final child

function list_term_ids_by_parent($parent_id = 0, &$term_ids, &$ordered_terms){
  $child_id = array_search($parent_id, $term_ids);

  if($child_id){
    $ordered_terms[] = $child_id;
    unset($term_ids[$child_id]);
  }

  if(!empty($term_ids)) order_terms($child_id, $term_ids, $ordered_terms);
}

这不是我的，我在某处找到的，可能是在这里或stackoverflow。这在输出上有点不同，因为它将生成一个级联术语列表，只有一个根，它有一个children属性，它将包含下一个术语及其children属性，依此类推。。

//$ordered\\u terms应该是如上所述的空数组

function sort_terms_hierarchically(&$terms, &$ordered_terms, $parentId = 0){
  foreach($cats as $i => $cat){
    if($cat->parent == $parentId){
      $into[$cat->term_id] = $cat;
      unset($cats[$i]);
    }
  }

  foreach ($into as $topCat) {
    $topCat->children = array();
    sort_terms_hierarchically($cats, $topCat->children, $topCat->term_id);
  }
}