Displaying first level parent and co-children of that parent page - php

Question

I've been trying to set up a basic sidebar in Wordpress that has a couple conditions.
If it's a top level page, display the first level of children
If it's a child page, display the parent as well as its siblings
I'm getting some results with this, but it's adding pages that aren't directly children.
<?php
if($post->post_parent)
$children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0");
else
$children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0");
if ($children) { ?>
<?php echo '<h4>Explore ' . get_the_title($parent[1]) . '</h4>'; ?>
<?php echo $children; ?>

Answer 1

There are 2 parts to this question
Limit the children to just 1 level: You can pass depth into wp_list_pages(), to can specify the level of hierarchy.
If its a child page, include the parent - but only the parent and not its siblings - in the list.
To add the parent to the list, you need to do things a little differently - you must first compile a a list of the ids of all the pages you want to get, and pass that into wp_list_pages.
The following code is untested, but the logic should be right:
if($post->post_parent){
// get a list of all the children of the parent page
$pages = get_pages(array('child_of'=>$post->post_parent));
if ($pages) {
// get the ids for the pages in a comma-delimited string
foreach ($pages as $page)
$page_ids[] = $page->ID;
$siblings = implode(',',$page_ids);
// $pages_to_get is a string with all the ids we want to get, i.e. parent & siblings
$pages_to_get = $post->post_parent.','.$siblings;
// use "include" to get only the pages in our $pages_to_get
$children = wp_list_pages("include=".$pages_to_get."&echo=0");
}
}
else{
// get pages that direct children of this page: depth=1
$children = wp_list_pages("title_li=&child_of=".$post->ID."&depth=1&echo=0");
}
// display the children:
if ($children) {
echo '<h4>Explore ' . get_the_title($parent[1]) . '</h4>';
echo $children;
}
?>