January 08, 2020

Create Custom Taxonomies in WordPress

Taxonomy is like a category for your post type. WordPress supports by default a builtin taxonomy "Category" for "Post". In this post we will register a custom taxonomy.

Create Custom Taxonomies in Wordpress

In WordPress a taxonomy is like a group for your post type which you can assign. Think of it as a category for a product. We created a custom post type "Property" in our post Create Custom Post Types in WordPress. Today we will create a custom taxonomy "City" and assign it to property. 


Custom Taxonomies in WordPress

WordPress has two built-in taxonomies "Category" and "Tag". But it still allows you to register custom taxonomies for your custom post types.

The WordPress function used to register a custom taxonomy is:
register_taxonomy( $slug, $post_types, $args );

  • $slug (string): A unique slug for our taxonomy i.e. "property-type".
  • $post_types (array): An array post type slugs for which these taxonomy will be registered.
  • $args (array): An array of arguments for this custom taxonomy containing label strings and other configuration options.

For complete understanding and example of this function visit WordPress Register Taxonomy page. 


Register a Custom Taxonomy in WordPress

We will first create a file custom_taxonomies.php in which we will use the function register_taxonomy to create our custom taxonomy. Then we will include this file in functions.php.

custom_taxonomies.php 

<?php 
add_action('init', 'theme_taxonomies');
function theme_taxonomies() {
    // --- Labels Array --- //
    
    // General name for the taxonomy, usually plural
    $labels['name'] = __('City', 'text-domain');

    // Name for one object of this taxonomy
    $labels['singular_name'] = __('City', 'text-domain');

    // Taxonomy name in menu
    $labels['menu_name'] = __('Cities', 'text-domain');

    // Label to signify all items in a submenu link
    $labels['all_items'] = __('All Cities', 'text-domain');

    // Label for adding a new term item button on list screen
    $labels['add_new_item'] = __('Add New City', 'text-domain');

    // Label for link to add a new term item
    $labels['new_item_name'] = __('New City', 'text-domain');

    // Label for link to edit term item
    $labels['edit_item'] = __('Edit City', 'text-domain');

    // Label for link to view term
    $labels['view_item'] = __('View City', 'text-domain');

    // Label for link to update a term item
    $labels['update_item'] = __('Update City', 'text-domain');

    // Label for search item button
    $labels['search_items'] = __('Search City', 'text-domain');

    // Label for text when no term is found
    $labels['not_found'] = __('No City Found', 'text-domain');

    // The labels array we prepare above
    $args['labels'] = $labels;

    // Whether a taxonomy is intended for use publicly
    $args['public'] = true;

    // Whether the taxonomy is publicly queryable
    $args['publicly_queryable'] = true;

    // Whether the taxonomy is hierarchical
    $args['hierarchical'] = false;

    // Whether to show the taxonomy in the admin menu
    $args['show_in_menu'] = true;

    // Sets the query var key for this taxonomy
    $args['query_var'] = true;

    // Triggers the handling of rewrites for this taxonomy
    $args['rewrite'] = [ 'slug' => 'property-city' ];

    // Wordpress function to register taxonomy
    register_taxonomy('property-city', ['property'], $args);
}
And that is it, you just registered a custom taxonomy in WordPress for a custom post type. Now all we need to do is include custom_taxonomies.php in functions.php. 
<?php include('custom_taxonomies.php');?>
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