"show option all" on list categories doesn't display taxonomy

Question

I have a wp_list_categories list set to display my custom taxonomy.

Everything works fine, and now I want to add a show_option_all link.

However, when the link is clicked it displays all default post type posts and none of the custom taxonomy. Obviously, the intent is to display all of the posts in this taxonomy, and only those.

$args = array('post_type' => 'design_asset', 'show_count' => 1, 'taxonomy' => 'asset_type', 'show_option_all' => 'Show All');
wp_list_categories($args);

Can this work? How?

Answer 1

wp_list_categories() is an odd function in that it's uniquely useful in certain situations with custom taxonomies but it was originally written before they even existed. (It was introduced in 2.1 and the taxonomy attribute was added in 3.0 (source).)

What you're seeing is a known issue with an associated bug report (filed two years ago, last activity four months ago). If you look at the source, you can see that the link is hard-coded to go to the page_for_posts page. So for now, you're looking for a work-around.

As @tomas-cot notes in their comment, the post_type argument in your code snippet isn't a valid argument for wp_list_categories(). However, I think what you're intending is for the show_option_all link to go the Post Type Archive page of your CPT.

You could do this with a walker class or maybe hacking the title_li argument, but since you have to wrap the function in <ul> tags anyway, I'd recommend the following (untested) code:

<?php
$list_cat_args = array(
    'show_count' => 1,
    'taxonomy' => 'asset_type',
    'use_desc_for_title' => 0 /* title attr bad for accessibility! */
);
// get the post type archive link
$all_posts_url = get_post_type_archive_link( 'design_asset' );
?>
<ul>
    <li><a href="<?php echo esc_url( $all_posts_url ); ?>">Show All</a></li>
    <?php wp_list_categories( $list_cat_args ); ?>
</ul>