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WP_Widget_Categories

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概述

WP_Widget_Categories 是 WordPress 核心类，用于实现分类目录小部件，显示分类列表或下拉菜单。它继承自 WP_Widget，提供配置和输出功能。

关键要点

  • 继承自 WP_Widget，用于创建分类目录小部件，支持列表或下拉形式显示。
  • 包含四个核心方法：__construct() 初始化小部件，widget() 输出内容，update() 处理设置更新，form() 生成设置表单。
  • 支持自定义标题、显示文章数量、层级结构和下拉菜单选项，通过过滤器如 widget_categories_dropdown_args 可调整参数。

代码示例

// 示例：创建 WP_Widget_Categories 实例并注册小部件
add_action( 'widgets_init', function() {
    register_widget( 'WP_Widget_Categories' );
} );

注意事项

  • 使用 wp_dropdown_categories() 函数生成下拉菜单，需注意 HTML ID 的唯一性以避免冲突。
  • 设置更新时使用 sanitize_text_field() 清理标题输入，确保安全性。
  • 小部件支持自定义选择性刷新和 REST API 实例显示，需在构造时配置相关选项。
📄 原文内容

Core class used to implement a Categories widget.

Description

See also

Methods

Name Description
WP_Widget_Categories::__construct Sets up a new Categories widget instance.
WP_Widget_Categories::form Outputs the settings form for the Categories widget.
WP_Widget_Categories::update Handles updating settings for the current Categories widget instance.
WP_Widget_Categories::widget Outputs the content for the current Categories widget instance.

Source

class WP_Widget_Categories extends WP_Widget {


	/**

	 * Sets up a new Categories widget instance.

	 *

	 * @since 2.8.0

	 */

	public function __construct() {

		$widget_ops = array(

			'classname'                   => 'widget_categories',

			'description'                 => __( 'A list or dropdown of categories.' ),

			'customize_selective_refresh' => true,

			'show_instance_in_rest'       => true,

		);

		parent::__construct( 'categories', __( 'Categories' ), $widget_ops );

	}


	/**

	 * Outputs the content for the current Categories widget instance.

	 *

	 * @since 2.8.0

	 * @since 4.2.0 Creates a unique HTML ID for the `<select>` element

	 *              if more than one instance is displayed on the page.

	 *

	 * @param array $args     Display arguments including 'before_title', 'after_title',

	 *                        'before_widget', and 'after_widget'.

	 * @param array $instance Settings for the current Categories widget instance.

	 */

	public function widget( $args, $instance ) {

		static $first_dropdown = true;


		$default_title = __( 'Categories' );

		$title         = ! empty( $instance['title'] ) ? $instance['title'] : $default_title;


		/** This filter is documented in wp-includes/widgets/class-wp-widget-pages.php */

		$title = apply_filters( 'widget_title', $title, $instance, $this->id_base );


		$count        = ! empty( $instance['count'] ) ? '1' : '0';

		$hierarchical = ! empty( $instance['hierarchical'] ) ? '1' : '0';

		$dropdown     = ! 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'   => $count,

			'hierarchical' => $hierarchical,

		);


		if ( $dropdown ) {

			printf( '<form action="%s" method="get">', esc_url( home_url() ) );

			$dropdown_id    = ( $first_dropdown ) ? 'cat' : "{$this->id_base}-dropdown-{$this->number}";

			$first_dropdown = false;


			echo '<label class="screen-reader-text" for="' . esc_attr( $dropdown_id ) . '">' . $title . '</label>';


			$cat_args['show_option_none'] = __( 'Select Category' );

			$cat_args['id']               = $dropdown_id;


			/**

			 * Filters the arguments for the Categories widget drop-down.

			 *

			 * @since 2.8.0

			 * @since 4.9.0 Added the `$instance` parameter.

			 *

			 * @see wp_dropdown_categories()

			 *

			 * @param array $cat_args An array of Categories widget drop-down arguments.

			 * @param array $instance Array of settings for the current widget.

			 */

			wp_dropdown_categories( apply_filters( 'widget_categories_dropdown_args', $cat_args, $instance ) );


			echo '</form>';


			ob_start();

			?>


<script>

( ( dropdownId ) => {

	const dropdown = document.getElementById( dropdownId );

	function onSelectChange() {

		setTimeout( () => {

			if ( 'escape' === dropdown.dataset.lastkey ) {

				return;

			}

			if ( dropdown.value && parseInt( dropdown.value ) > 0 && dropdown instanceof HTMLSelectElement ) {

				dropdown.parentElement.submit();

			}

		}, 250 );

	}

	function onKeyUp( event ) {

		if ( 'Escape' === event.key ) {

			dropdown.dataset.lastkey = 'escape';

		} else {

			delete dropdown.dataset.lastkey;

		}

	}

	function onClick() {

		delete dropdown.dataset.lastkey;

	}

	dropdown.addEventListener( 'keyup', onKeyUp );

	dropdown.addEventListener( 'click', onClick );

	dropdown.addEventListener( 'change', onSelectChange );

})( <?php echo wp_json_encode( $dropdown_id, JSON_HEX_TAG | JSON_UNESCAPED_SLASHES ); ?> );

</script>


			';

			}

			?>


			<ul>


			</ul>


			';

			}

		}


		echo $args['after_widget'];

	}


	/**

	 * Handles updating settings for the current Categories widget instance.

	 *

	 * @since 2.8.0

	 *

	 * @param array $new_instance New settings for this instance as input by the user via

	 *                            WP_Widget::form().

	 * @param array $old_instance Old settings for this instance.

	 * @return array Updated settings to save.

	 */

	public function update( $new_instance, $old_instance ) {

		$instance                 = $old_instance;

		$instance['title']        = sanitize_text_field( $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;

	}


	/**

	 * Outputs the settings form for the Categories widget.

	 *

	 * @since 2.8.0

	 *

	 * @param array $instance Current settings.

	 */

	public function form( $instance ) {

		// Defaults.

		$instance     = wp_parse_args( (array) $instance, array( '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' ); ?>"></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 esc_attr( $instance['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' ); ?>"></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' ); ?>"></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' ); ?>"></label>

		</p>

		</pre><p class="wporg-dot-link-list"><a href="https://developer.wordpress.org/reference/files/wp-includes/widgets/class-wp-widget-categories.php/">View all references</a> <a href="https://core.trac.wordpress.org/browser/tags/6.9.4/src/wp-includes/widgets/class-wp-widget-categories.php#L17">View on Trac</a> <a href="https://github.com/WordPress/wordpress-develop/blob/6.9.4/src/wp-includes/widgets/class-wp-widget-categories.php#L17-L222">View on GitHub</a></p></section>


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Core base class extended to register widgets.

Changelog

Version Description
2.8.0 Introduced.