[WordPress] カテゴリーリストのマークアップを変更する

    $args = array(
	'show_option_all'    => '',
	'orderby'            => 'name',
	'order'              => 'ASC',
	'style'              => 'list',
	'show_count'         => 0,
	'hide_empty'         => 1,
	'use_desc_for_title' => 1,
	'child_of'           => 0,
	'feed'               => '',
	'feed_type'          => '',
	'feed_image'         => '',
	'exclude'            => '',
	'exclude_tree'       => '',
	'include'            => '',
	'hierarchical'       => 1,
	'title_li'           => __( 'Categories' ),
	'show_option_none'   => __( '' ),
	'number'             => null,
	'echo'               => 1,
	'depth'              => 0,
	'current_category'   => 0,
	'pad_counts'         => 0,
	'taxonomy'           => 'category',
	'walker'             => null
    );
    wp_list_categories( $args ); 

<li class="categories">カテゴリー
  <ul>
	<li class="cat-item cat-item-1"><a href="//localhost:3000/category/category1/">カテゴリー１</a></li>
	<li class="cat-item cat-item-2"><a href="//localhost:3000/category/category2/">カテゴリー２</a></li>
  </ul>
</li>

wp_list_categories( array('title_li' => null, 'depth'=> 2) ); 

<li class="cat-item cat-item-1"><a href="//localhost:3000/category/category-1/">カテゴリー１</a>
    <ul class=“children”>
       <li class=“cat-item cat-item-6"><a href=“//localhost:3000/category/category-1/category-7/“>カテゴリー7</a></li>
       <li class=“cat-item cat-item-7”><a href=“//localhost:3000/category/category-1/category-8/“>カテゴリー8</a></li>
       <li class=“cat-item cat-item-11”><a href=“//localhost:3000/category/category-1/category-9/“>カテゴリー9</a></li>
     </ul>
 </li>
<li class="cat-item cat-item-2"><a href="//localhost:3000/category/category-2/">カテゴリー２</a></li>
<li class="cat-item cat-item-3"><a href="//localhost:3000/category/category-3/">カテゴリー３</a>
  <ul class="children">
	<li class="cat-item cat-item-4"><a href="//localhost:3000/category/category-3/category-4/">カテゴリー４</a>
</li>
	<li class="cat-item cat-item-5"><a href="//localhost:3000/category/category-3/category-4/">カテゴリー４</a>
</li>
	<li class="cat-item cat-item-15"><a href="//localhost:3000/category/category-3/category-5/">カテゴリー5</a>
</li>
</ul>
</li>

<?php
/**
 * Bootstrapのアコーディオン用マークアップをする
 * カテゴリー用カスタムウォーカー
 * wp_list_categories の walkerオプションでセットするとマークアップが切り替わる
 * 'walker' => new \sample\walker\AccordionCategory
 */

namespace sample\walker;

class AccordionCategory extends \Walker_Category {
// ここに処理を書く
}

  /**
   * Starts the element output.
   *
   * @since 2.1.0
   * @access public
   *
   * @see Walker::start_el()
   *
   * @param string $output   Passed by reference. Used to append additional content.
   * @param object $category Category data object.
   * @param int    $depth    Optional. Depth of category in reference to parents. Default 0.
   * @param array  $args     Optional. An array of arguments. See wp_list_categories(). Default empty array.
   * @param int    $id       Optional. ID of the current category. Default 0.
   */
  public function start_el( &$output, $category, $depth = 0, $args = array(), $id = 0 ) {

    $header = '';
    $body = '';
    $link = '';
    $container_id = 'site-category';
    $item_id = 'cat-' . $category->slug;
    $collapse_id = 'collapse-' . $category->slug;
    
    /** This filter is documented in wp-includes/category-template.php */
    $cat_name = apply_filters(
      'list_cats',
      esc_attr( $category->name ),
      $category
    );

    //子カテゴリ
    $child_categories = get_term_children($category->term_id, 'category');

    $child_categories_count = count($child_categories);

    // 親カテゴリー
    if($depth === 0) {
      // 子カテゴリーがある
      if ($child_categories_count > 0) {
        $header .= '<div class="accordion-item">';
        $header .= '<h3 class="accordion-header" id="' . $item_id . '">';
        $header .= '<button class="accordion-button collapsed" type="button" data-bs-toggle="collapse" data-bs-target="#' . $collapse_id . '" aria-expanded="false" aria-controls="' . $collapse_id . '">';
        $header .= $cat_name . '</button></h3>';
        
        $body .= '<div id="' . $collapse_id . '" class="accordion-collapse collapse" aria-labelledby="' . $item_id . '" data-bs-parent="#' . $container_id . '">';
        $body .= '<div class="accordion-body">';
      } else {
        // 子カテゴリーがない
        $header .= '<div>';
        $header .= '<div class="px-1">';
        $header .= '<a class="btn btn-light p-3 d-block text-start bg-white" ';
        $header .= 'href="' . esc_url( get_term_link( $category ) ) . '">';
        $header .= $cat_name;
        $header .= '</a>';
      }

    } else {
      // 子カテゴリー
      $link .= '<a class="d-inline-flex align-items-center rounded py-3" ';
      $link .= 'href="' . esc_url( get_term_link( $category ) ) . '">';
      $link .= $cat_name;
      $link .= '</a>';
      $body .= '<li>' . $link . '</li>';
    }

    $output .= $header;
    $output .= $body;
  }

  /**
	 * Ends the element output, if needed.
	 *
	 * The $args parameter holds additional values that may be used with the child class methods.
	 *
	 * @since 2.1.0
	 * @abstract
	 *
	 * @param string $output Used to append additional content (passed by reference).
	 * @param object $object The data object.
	 * @param int    $depth  Depth of the item.
	 * @param array  $args   An array of additional arguments.
	 */
	public function end_el( &$output, $object, $depth = 0, $args = array() ) {
    // カテゴリールート
    if($depth === 0) {
      $output .= '</div></div>';
    }
  }

  /**
	 * Starts the list before the elements are added.
	 *
	 * @since 2.1.0
	 *
	 * @see Walker::start_lvl()
	 *
	 * @param string $output Used to append additional content. Passed by reference.
	 * @param int    $depth  Optional. Depth of category. Used for tab indentation. Default 0.
	 * @param array  $args   Optional. An array of arguments. Will only append content if style argument
	 *                       value is 'list'. See wp_list_categories(). Default empty array.
	 */
	public function start_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat("\t", $depth);
		$output .= "$indent<ul class='list-unstyled fw-normal m-0 p-0 small'>\n";
  }

  /**
	 * Ends the list of after the elements are added.
	 *
	 * The $args parameter holds additional values that may be used with the child
	 * class methods. This method finishes the list at the end of output of the elements.
	 *
	 * @since 2.1.0
	 * @abstract
	 *
	 * @param string $output Used to append additional content (passed by reference).
	 * @param int    $depth  Depth of the item.
	 * @param array  $args   An array of additional arguments.
	 */
	public function end_lvl( &$output, $depth = 0, $args = array() ) {
    $output .= '</ul>';
  }

require( get_template_directory() . '/walker/accordion-category.php' );

wp_list_categories( array( 'depth'  => 2, 'walker' => new \sample\walker\AccordionCategory ) );