I’m currently struggling with displaying custom taxonomy terms in a WordPress theme, and I can’t seem to get the desired output. I’m using a custom taxonomy called genre, which is attached to a custom post type. The problem is how I need to display the taxonomy terms on a single post page.
Desired Output:
I need to display parent categories with their subcategories in the following format:
Fiction (Cyberpunk, Timepunk (Steampunk/Paropunk)) | Fantasy (Heroic Fantasy)
The Problem:
At the moment, I’m using the following code in my functions.php file to generate the output:
function get_taxonomy_output($terms) {
if (!is_wp_error($terms) && !empty($terms)) {
$parent_cats = array();
$child_cats = array();
// Sort categories into parent and child categories
foreach ($terms as $term) {
if ($term->parent == 0) { // This is the parent category
$parent_cats[$term->term_id] = $term;
} else { // This is a child category
$child_cats[$term->parent][] = $term;
}
}
// Form the output line
$output = array();
foreach ($parent_cats as $parent_id => $parent_cat) {
$output[] = build_category_output($parent_cat, $child_cats);
}
return implode(', ', $output);
}
return '';
}
function build_category_output($parent_cat, $child_cats) {
$parent_link = '<a href="' . esc_url(get_term_link($parent_cat)) . '">' . esc_html($parent_cat->name) . '</a>';
$output = $parent_link;
if (!empty($child_cats[$parent_cat->term_id])) {
$children = array();
foreach ($child_cats[$parent_cat->term_id] as $child_cat) {
// Check if the current subcategory has its own subcategories
if (!empty($child_cats[$child_cat->term_id])) {
$children[] = build_category_output($child_cat, $child_cats); // Recursively build child categories
} else {
$children[] = '<a href="' . esc_url(get_term_link($child_cat)) . '">' . esc_html($child_cat->name) . '</a>';
}
}
$output .= ' (' . implode(', ', $children) . ')';
}
return $output;
}
And in single.php I have this code
$categories = get_the_terms(get_the_ID(), 'genre');
$output_genre = get_taxonomy_output($categories);
In the place where I want to display subcategories, this is displayed:
Fiction and Fantasy (Fiction (Cyberpunk, Timepunk (Steampunk/Paropunk), Fantasy (Heroic Fantasy)).
It should be like this:
Fiction (Cyberpunk, Timepunk (Steampunk/Paropunk) | Fantasy (Heroic Fantasy)
I attach an image of how it looks in the admin panel.
I am trying to make code that will be as optimized as possible and meet all WordPress development standards.
1
It looks like there is a small issue with get_taxonomy_output function, so could you please try to replace given line of code in that function.
return implode(', ', $output);
with the given code.
return implode(' | ', $output); // Here we are using ' | ' as the separator for parent categories.
It should works for you.
get_taxonomy_output Function:
Uses implode(' | ', $output) to separate parent categories with |.
build_category_output Function:
Recursively builds the output for child categories and maintains proper formatting with parentheses.
Updated Code:
function get_taxonomy_output($terms) {
if (!is_wp_error($terms) && !empty($terms)) {
$parent_cats = array();
$child_cats = array();
// Sort categories into parent and child categories
foreach ($terms as $term) {
if ($term->parent == 0) { // This is the parent category
$parent_cats[$term->term_id] = $term;
} else { // This is a child category
$child_cats[$term->parent][] = $term;
}
}
// Form the output line
$output = array();
foreach ($parent_cats as $parent_id => $parent_cat) {
$output[] = build_category_output($parent_cat, $child_cats);
}
// Return the output with a ' | ' delimiter
return implode(' | ', $output);
}
return '';
}
function build_category_output($parent_cat, $child_cats) {
$parent_link = '<a href="' . esc_url(get_term_link($parent_cat)) . '">' . esc_html($parent_cat->name) . '</a>';
$output = $parent_link;
if (!empty($child_cats[$parent_cat->term_id])) {
$children = array();
foreach ($child_cats[$parent_cat->term_id] as $child_cat) {
// Check if the current subcategory has its own subcategories
if (!empty($child_cats[$child_cat->term_id])) {
$children[] = build_category_output($child_cat, $child_cats); // Recursively build child categories
} else {
$children[] = '<a href="' . esc_url(get_term_link($child_cat)) . '">' . esc_html($child_cat->name) . '</a>';
}
}
$output .= ' (' . implode(', ', $children) . ')';
}
return $output;
}