Add viaraible to wp_list_categories

Short answer: You can’t.

Longer answer: You’d need to build your own category listing function – perhaps using get_categories().

Hmm… I’m listing the taxonomies of a custom post type. So not sure it would work. Could you use preg_replace just to tack it onto the end?

Found this which adds an ‘id=xx’ to the ‘li’ but doesn’t alter the url.

function add_id_from_slug($wp_list_categories) {
		$pattern = '/class=/';
		$replacement = 'id="xx" class=';
		return preg_replace($pattern, $replacement, $wp_list_categories);
}
add_filter('wp_list_categories','add_id_from_slug');

Do you know if it could be altered to add to the the url? Otherwise it’s the dreaded walker class for me.

Thanks.

Aha! so got it working using a filter.

function filter_categories($output, $args=array()){
      return preg_replace('/(\<a\shref=\"?[^\>]+?)\"/', '$1?area=map"', $output);
}
add_filter('wp_list_categories', 'filter_categories', 10, 2);

outputs: https://www.mysite.com/area/central/?id=map

Last hurdle. How do I get it to add that filter only from a certain page.

I need to get if is_page in there but it won’t work, probably due to my bad php.

Any pointers appreciated.

Thanks

No worries got it working using ‘$id = get_the_title();’ then on the next page I’ll use a simple get_id and if, else to display different content. Quite static really, but works for what i need. final code:

function filter_categories($output, $args=array()) {
	$id = get_the_title();
	return preg_replace('/(\<a\shref=\"?[^\>]+?)\"/', '$1?id='. $id .'"', $output);
		}
	add_filter('wp_list_categories', 'filter_categories', 10, 2);