Wordpress is_child() for Advanced Navigation

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Development, Wordpress / 5.4.09 / 3088 Comments2009-05-05+03%3A29%3A20kevin /
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WordPress lacks one key feature for advanced developers using it as a CMS platform. That feature is the is_child() (or would be) function. If your familiar with WordPress Theme Development you have probably ran into the following Conditional Tags from time to time:

is_home()
is_front_page()
is_single()
is_sticky()
is_page()

If you ever want to have a sidebar navigation display the next level of child pages, you would need is_child() to do so.

// is_child()
function is_child($parent) {
	global $wp_query;
	if ($wp_query->post->post_parent == $parent) {
		$return = true;
	}
	else {
		$return = false;
	}
	return $return;
}

Usage

To use the conditional in your theme(s), add the code above to functions.php. This only takes the Post IDas an argument, so you’ll need to use something like is_child(201); because is_child(‘Services’); will not work.

Working Example

The inner Services pages on kevinleary.net use this function to create a dynamic breadcrumb. I know there are plugins for this but I was looking for something simple and quick.

<?php if(is_child(221)) { ?>
		<h1 class="post-title"><a href="/services/">Services</a> <em>&gt;</em> <?php the_title(); ?></h1>
<?php } else { ?>
		<h1 class="post-title"><?php the_title(); ?></h1>
<?php } ?>