Code Snippet to Create a Custom Taxonomy in WordPress

Creating a Custom Taxonomy in WordPress

Custom Code Solution

This code creates a custom taxonomy that you can use to organize your posts or custom post types. Place this code in your theme's functions.php file or in a site-specific plugin.

Basic taxonomy registration code for a 'Genre' taxonomy:

function register_genre_taxonomy() {
    $labels = array(
        'name'          => 'Genres',
        'singular_name' => 'Genre',
        'menu_name'     => 'Genres',
        'all_items'     => 'All Genres',
        'edit_item'     => 'Edit Genre',
        'add_new_item'  => 'Add New Genre'
    );

    $args = array(
        'labels'            => $labels,
        'hierarchical'      => true,  // Set to false for tags-like behavior
        'public'            => true,
        'show_ui'          => true,
        'show_admin_column' => true,
        'show_in_rest'     => true,  // Enable Gutenberg editor support
        'query_var'        => true,
        'rewrite'          => array('slug' => 'genre')
    );

    register_taxonomy('genre', 'post', $args);
}
add_action('init', 'register_genre_taxonomy');

Advanced Version

This extended version includes a custom taxonomy for multiple post types with additional features:

function register_custom_taxonomy() {
    // Change these values to match your needs
    $taxonomy_name = 'genre';
    $taxonomy_labels = array(
        'name'              => 'Genres',
        'singular_name'     => 'Genre'
    );
    $post_types = array('post', 'custom_post_type');  // Add your post types here

    $args = array(
        'labels'            => $taxonomy_labels,
        'hierarchical'      => true,
        'public'            => true,
        'show_ui'          => true,
        'show_admin_column' => true,
        'show_in_rest'     => true,
        'query_var'        => true,
        'rewrite'          => array(
            'slug'         => $taxonomy_name,
            'with_front'   => true,
            'hierarchical' => true
        ),
        'capabilities'     => array(
            'manage_terms' => 'manage_categories',
            'edit_terms'   => 'manage_categories',
            'delete_terms' => 'manage_categories',
            'assign_terms' => 'edit_posts'
        )
    );

    register_taxonomy($taxonomy_name, $post_types, $args);
}
add_action('init', 'register_custom_taxonomy');

Important Notes

• After adding the code, visit Settings > Permalinks and click "Save Changes" to flush rewrite rules
• Set hierarchical to true for category-like behavior or false for tag-like behavior
• Change the taxonomy name, labels, and post types to match your needs
• The show_in_rest parameter enables Gutenberg editor support

Plugin Alternative

If you prefer a plugin solution, these options are reliable:

• Custom Post Type UI - User-friendly interface for creating taxonomies
• Pods - Advanced content type and field management

Both plugins provide GUI interfaces for creating custom taxonomies without coding.

Usage Example

After registration, you can assign terms to posts using:

wp_set_object_terms($post_id, 'Mystery', 'genre');

Query posts by taxonomy:

$args = array(
    'post_type' => 'post',
    'tax_query' => array(
        array(
            'taxonomy' => 'genre',
            'field'    => 'slug',
            'terms'    => 'mystery'
        )
    )
);
$query = new WP_Query($args);