default-widgets.phpの533行目当たりから始まる部分が
カテゴリ一覧ウィジェットを生成する部分みたいです。
/** * Categories widget class * * @since 2.8.0 */ class WP_Widget_Categories extends WP_Widget { public function __construct() { $widget_ops = array('classname' => 'widget_categories', 'description' => __( "A list or dropdown of categories." ) ); parent::__construct('categories', __('Categories'), $widget_ops); } public function widget( $args, $instance ) { /** This filter is documented in wp-includes/default-widgets.php */ $title = apply_filters( 'widget_title', empty( $instance['title'] ) ? __( 'Categories' ) : $instance['title'], $instance, $this->id_base ); $c = ! empty( $instance['count'] ) ? '1' : '0'; $h = ! empty( $instance['hierarchical'] ) ? '1' : '0'; $d = ! empty( $instance['dropdown'] ) ? '1' : '0'; echo $args['before_widget']; if ( $title ) { echo $args['before_title'] . $title . $args['after_title']; } $cat_args = array( 'orderby' => 'name', 'show_count' => $c, 'hierarchical' => $h); if ( $d ) { $cat_args['show_option_none'] = __('Select Category'); /** * Filter the arguments for the Categories widget drop-down. * * @since 2.8.0 * * @see wp_dropdown_categories() * * @param array $cat_args An array of Categories widget drop-down arguments. */ wp_dropdown_categories( apply_filters( 'widget_categories_dropdown_args', $cat_args ) ); ?> <script type='text/javascript'> /* <![CDATA[ */ var dropdown = document.getElementById("cat"); function onCatChange() { if ( dropdown.options[dropdown.selectedIndex].value > 0 ) { location.href = "<?php echo home_url(); ?>/?cat="+dropdown.options[dropdown.selectedIndex].value; } } dropdown.onchange = onCatChange; /* ]]> */ </script> <?php } else { ?> <div id="right_categories"> <ul> <?php $cat_args['title_li'] = ''; /** * Filter the arguments for the Categories widget. * * @since 2.8.0 * * @param array $cat_args An array of Categories widget options. */ wp_list_categories( apply_filters( 'widget_categories_args', $cat_args ) ); ?> </ul> </div> <?php } echo $args['after_widget']; } public function update( $new_instance, $old_instance ) { $instance = $old_instance; $instance['title'] = strip_tags($new_instance['title']); $instance['count'] = !empty($new_instance['count']) ? 1 : 0; $instance['hierarchical'] = !empty($new_instance['hierarchical']) ? 1 : 0; $instance['dropdown'] = !empty($new_instance['dropdown']) ? 1 : 0; return $instance; } public function form( $instance ) { //Defaults $instance = wp_parse_args( (array) $instance, array( 'title' => '') ); $title = esc_attr( $instance['title'] ); $count = isset($instance['count']) ? (bool) $instance['count'] :false; $hierarchical = isset( $instance['hierarchical'] ) ? (bool) $instance['hierarchical'] : false; $dropdown = isset( $instance['dropdown'] ) ? (bool) $instance['dropdown'] : false; ?> <p><label for="<?php echo $this->get_field_id('title'); ?>"><?php _e( 'Title:' ); ?></label> <input class="widefat" id="<?php echo $this->get_field_id('title'); ?>" name="<?php echo $this->get_field_name('title'); ?>" type="text" value="<?php echo $title; ?>" /></p> <p><input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('dropdown'); ?>" name="<?php echo $this->get_field_name('dropdown'); ?>"<?php checked( $dropdown ); ?> /> <label for="<?php echo $this->get_field_id('dropdown'); ?>"><?php _e( 'Display as dropdown' ); ?></label><br /> <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('count'); ?>" name="<?php echo $this->get_field_name('count'); ?>"<?php checked( $count ); ?> /> <label for="<?php echo $this->get_field_id('count'); ?>"><?php _e( 'Show post counts' ); ?></label><br /> <input type="checkbox" class="checkbox" id="<?php echo $this->get_field_id('hierarchical'); ?>" name="<?php echo $this->get_field_name('hierarchical'); ?>"<?php checked( $hierarchical ); ?> /> <label for="<?php echo $this->get_field_id('hierarchical'); ?>"><?php _e( 'Show hierarchy' ); ?></label></p> <?php } }
559行目からの部分がカテゴリ一覧を抽出する部分の様で、ここに depth という引数を記入します。 depth => 1 が’第一階層のみを表示’のようです。なので
$cat_args = array('depth' => '1', 'orderby' => 'name', 'show_count' => $c, 'hierarchical' => $h);
で親カテゴリだけが表示されます。
