Recently, a friend sent some code over to me, and I thought it would be hugely beneficial for all to see it, especially in this series. For a custom post type that could have a lot of posts (like books) it proves priceless. You can find the original code here.
[php]
// Adding a Taxonomy Filter to Admin List for a Custom Post Type
add_action( 'restrict_manage_posts', 'my_restrict_manage_posts' );
function my_restrict_manage_posts() {
// only display these taxonomy filters on desired custom post_type listings
global $typenow;
if ($typenow == 'books_ibm') {
// create an array of taxonomy slugs you want to filter by - if you want to retrieve all taxonomies, could use get_taxonomies() to build the list
$filters = array('genre', 'writer');
foreach ($filters as $tax_slug) {
// retrieve the taxonomy object
$tax_obj = get_taxonomy($tax_slug);
$tax_name = $tax_obj->labels->name;
// output html for taxonomy dropdown filter
echo "<select name='$tax_slug' id='$tax_slug' class='postform'>";
echo "<option value=''>Show All $tax_name</option>";
generate_taxonomy_options($tax_slug,0,0);
echo "</select>";
}
}
}
function generate_taxonomy_options($tax_slug, $parent = '', $level = 0) {
$args = array('show_empty' => 1);
if(!is_null($parent)) {
$args = array('parent' => $parent);
}
$terms = get_terms($tax_slug,$args);
$tab='';
for($i=0;$i<$level;$i++){
$tab.='--';
}
foreach ($terms as $term) {
// output each select option line, check against the last $_GET to show the current option selected
echo '<option value='. $term->slug, $_GET[$tax_slug] == $term->slug ? ' selected="selected"' : '','>' .$tab. $term->name .' (' . $term->count .')</option>';
generate_taxonomy_options($tax_slug, $term->term_id, $level+1);
}
}
[/php]
Please let me know what you think!?