WordPress 主页显示设置增加文章选择

// 阅读设置主页显示可以选择文章
class CustomFrontPage {
	private static $instance;
	public static function get_instance() {
		return isset( self::$instance ) ? self::$instance : new self();
	}

	private function __construct() {
		self::$instance = $this;
		if ( is_admin() ) {
			add_filter( \'wp_dropdown_pages\', array( $this, \'wp_dropdown_pages\' ) );
		} else {
			add_action( \'pre_get_posts\', array( $this, \'pre_get_posts\' ) );
			add_action( \'template_redirect\', array( $this, \'template_redirect\' ) );
		}
	}

	public function wp_dropdown_pages( $output ) {
		global $pagenow;
		if ( ( \'options-reading.php\' === $pagenow || \'customize.php\' === $pagenow ) && preg_match( \'#page_on_front#\', $output ) ) {
			$output = $this->posts_dropdown();
		}

		return $output;
	}

	protected function posts_dropdown( $post_type = \'any\' ) {
		$output = \'\';
		if ( \'any\' !== $post_type && ! post_type_exists( $post_type ) ) {
			$post_type = \'page\';
		}
		$posts = get_posts(
			array(
				\'posts_per_page\' => - 1,
				\'orderby\'        => \'title\',
				\'order\'          => \'ASC\',
				\'post_type\'      => $post_type,
				\'post_status\'    => \'publish\',
			)
		);

		$front_page_id = get_option( \'page_on_front\' );

		$select  = __( \'Select\' );
		$output .= \'<select name=\"page_on_front\" id=\"page_on_front\">\';
		$output .= \"<option value=\\\"0\\\">&mdash; {$select} &mdash;</option>\";
		foreach ( $posts as $post ) {
			$selected      = selected( $front_page_id, $post->ID, false );
			$post_type_obj = get_post_type_object( $post->post_type );

			$output .= \"<option value=\\\"{$post->ID}\\\"{$selected}>{$post->post_title} ({$post_type_obj->labels->singular_name})</option>\";
		}
		$output .= \'</select>\';

		return $output;
	}

	public function pre_get_posts( $query ) {
		if ( $query->is_main_query() ) {
			$post_type = $query->get( \'post_type\' );
			$page_id   = $query->get( \'page_id\' );
			if ( empty( $post_type ) && ! empty( $page_id ) ) {
				$query->set( \'post_type\', get_post_type( $page_id ) );
			}
		}
	}

	public function template_redirect() {
		global $post;
		if ( is_singular() && ! is_front_page() && absint( get_option( \'page_on_front\' ) ) === $post->ID ) {
			wp_safe_redirect( site_url(), 301 );
		}
	}
}

CustomFrontPage::get_instance();