WordPress函数get_post_ancestors()获取所有的父页面

描述：

获取所有的父页面

用法：

<?php get_post_ancestors( $post ) ?>

参数：

$post

(mixed) (必填) 文章 ID

默认值: None

示例：

此示例返回层级最高的页面{slug}，并将其用作Body_Class，因此父级和所有子级将具有相同的Body_Class！

<?php
/* Get the Page Slug to Use as a Body Class, this will only return a value on pages! */
$class = '';
/* is it a page */
if( is_page() ) { 
	global $post;
        /* Get an array of Ancestors and Parents if they exist */
	$parents = get_post_ancestors( $post->ID );
        /* Get the top Level page->ID count base 1, array base 0 so -1 */ 
	$id = ($parents) ? $parents[count($parents)-1]: $post->ID;
	/* Get the parent and set the $class with the page slug (post_name) */
        $parent = get_post( $id );
	$class = $parent->post_name;
}
?>

<body <?php body_class( $class ); ?>>

源文件：

/**
 * Retrieve ancestors of a post.
 *
 * @since 2.5.0
 *
 * @param int|WP_Post $post Post ID or post object.
 * @return array Ancestor IDs or empty array if none are found.
 */
function get_post_ancestors( $post ) {
	$post = get_post( $post );

	if ( ! $post || empty( $post->post_parent ) || $post->post_parent == $post->ID )
		return array();

	$ancestors = array();

	$id = $ancestors[] = $post->post_parent;

	while ( $ancestor = get_post( $id ) ) {
		// Loop detection: If the ancestor has been seen before, break.
		if ( empty( $ancestor->post_parent ) || ( $ancestor->post_parent == $post->ID ) || in_array( $ancestor->post_parent, $ancestors ) )
			break;

		$id = $ancestors[] = $ancestor->post_parent;
	}

	return $ancestors;
}