Understanding Custom Post Types and Taxonomies

Oct 13, 2025 by wbrum.org 124 views

Introduction

When creating custom post types (CPTs) in WordPress, it's essential to understand how to structure and filter their URLs. In this article, we'll explore how to filter custom post type URLs by taxonomy, specifically categories. We'll use the example of a CPT called "news" and default categories like "IT" and "recruitment."

Understanding Custom Post Types and Taxonomies

Custom post types are a powerful feature in WordPress that allows developers to create custom content types beyond the standard post, page, and attachment types. Taxonomies, on the other hand, are a way to categorize and organize custom post types. In this example, we'll use the default categories "IT" and "recruitment" as taxonomies to filter our custom post type "news."

Creating a Custom Post Type

To create a custom post type, you'll need to add the following code to your theme's functions.php file or a custom plugin:

function create_news_post_type() {
  register_post_type('news',
    array(
      'labels' => array(
        'name' => __( 'News' ),
        'singular_name' => __( 'News' )
      ),
      'public' => true,
      'has_archive' => true,
      'supports' => array( 'title', 'editor', 'thumbnail' )
    )
  );
}
add_action( 'init', 'create_news_post_type' );

This code registers a custom post type called "news" with the following properties:

Labels: The name and singular name of the post type.
Public: Makes the post type visible in the WordPress admin interface.
Has Archive: Enables the post type to have an archive page.
Supports: Enables the post type to support title, editor, and thumbnail fields.

Adding Taxonomies

To add taxonomies to our custom post type, we'll use the register_taxonomy function. We'll create two taxonomies, "IT" and "recruitment," and associate them with our custom post type "news":

function create_news_taxonomies() {
  // Create taxonomy
  register_taxonomy(
    'news_category',
    'news',
    array(
      'labels' => array(
        'name' => __( 'Categories' ),
        'singular_name' => __( 'Category' )
      ),
      'hierarchical' => true,
      'query_var' => true,
      'rewrite' => array( 'slug' => 'news/category' )
    )
  );
// Create taxonomy
register_taxonomy(
'news_type',
'news',
array(
'labels' => array(
'name' => __( 'Types' ),
'singular_name' => __( 'Type' )
),
'hierarchical' => true,
'query_var' => true,
'rewrite' => array( 'slug' => 'news/type' )
)
);
}
add_action( 'init', 'create_news_taxonomies' );

This code registers two taxonomies, "news_category" and "news_type," and associates them with our custom post type "news." The taxonomies have the following properties:

Labels: The name and singular name of the taxonomy.
Hierarchical: Makes the taxonomy hierarchical, allowing for parent-child relationships.
Query Var: Enables the taxonomy to be used as a query variable.
Rewrite: Enables the taxonomy to be rewritten as a slug.

Filtering Custom Post Type URLs by Taxonomy

To filter our custom post type URLs by taxonomy, we'll use the add_rewrite_rule function. We'll create two rewrite rules, one for each taxonomy:

function add_news_rewrite_rules() {
  add_rewrite_rule(
    '^news/([^/]+)/?$', 'index.php?post_type=news&news_category=$matches[1]', 'top'
  );
add_rewrite_rule(
'^news/([/]+)/([^/]+)/? $&#39;, &#39;index.php?post_type=news&amp;news_category=$ matches[1]&news_type=$matches[2]', 'top'
);
}
add_action( 'init', 'add_news_rewrite_rules' );

This code adds two rewrite rules to our custom post type URLs:

The first rule filters by the "news_category" taxonomy, using the slug "news/category" as the query variable.
The second rule filters by both the "news_category" and "news_type" taxonomies, using the slugs "news/category" and "news/type" as query variables.

Displaying Archive Pages

To display archive pages for our custom post type, we'll use the get_post_type_archive_link function. We'll create two archive pages, one for each taxonomy:

function display_news_archive_pages() {
  $news_category_archive_link = get_post_type_archive_link('news');
  $news_type_archive_link = get_post_type_archive_link('news');
echo '<a href="' . $news_category_archive_link . '">News Category Archive</a>';
echo '<a href="' . $news_type_archive_link . '">News Type Archive</a>';
}

This code displays two archive pages, one for each taxonomy, using the get_post_type_archive_link function.

Conclusion

In this article, we've explored how to filter custom post type URLs by taxonomy in WordPress. We've created a custom post type called "news" and associated it with two taxonomies, "IT" and "recruitment." We've used the add_rewrite_rule function to create two rewrite rules, one for each taxonomy, and displayed archive pages for each taxonomy using the get_post_type_archive_link function. With this knowledge, you can now filter your custom post type URLs by taxonomy and display archive pages for each taxonomy.

Additional Resources

Example Use Cases

Creating a custom post type for news articles and filtering them by category.
Creating a custom post type for products and filtering them by category and type.
Creating a custom post type for events and filtering them by category and date.

Code Snippets

create_news_post_type function: Creates a custom post type called "news" with the following properties: labels, public, has_archive, and supports.
create_news_taxonomies function: Creates two taxonomies, "news_category" and "news_type," and associates them with our custom post type "news."
add_news_rewrite_rules function: Adds two rewrite rules to our custom post type URLs, one for each taxonomy.
display_news_archive_pages function: Displays two archive pages, one for each taxonomy, using the get_post_type_archive_link function.
Custom Post Type URL - Filter by Taxonomy: Q&A =====================================================

Introduction

In our previous article, we explored how to filter custom post type URLs by taxonomy in WordPress. We created a custom post type called "news" and associated it with two taxonomies, "IT" and "recruitment." We used the add_rewrite_rule function to create two rewrite rules, one for each taxonomy, and displayed archive pages for each taxonomy using the get_post_type_archive_link function. In this article, we'll answer some frequently asked questions about filtering custom post type URLs by taxonomy.

Q: What is the difference between a custom post type and a taxonomy?

A: A custom post type is a type of content in WordPress that is not a standard post, page, or attachment. A taxonomy, on the other hand, is a way to categorize and organize custom post types. Think of a custom post type as a type of content, and a taxonomy as a way to group that content.

Q: How do I create a custom post type?

A: To create a custom post type, you'll need to add the following code to your theme's functions.php file or a custom plugin:

function create_news_post_type() {
  register_post_type('news',
    array(
      'labels' => array(
        'name' => __( 'News' ),
        'singular_name' => __( 'News' )
      ),
      'public' => true,
      'has_archive' => true,
      'supports' => array( 'title', 'editor', 'thumbnail' )
    )
  );
}
add_action( 'init', 'create_news_post_type' );

This code registers a custom post type called "news" with the following properties: labels, public, has_archive, and supports.

Q: How do I create a taxonomy?

A: To create a taxonomy, you'll need to add the following code to your theme's functions.php file or a custom plugin:

function create_news_taxonomies() {
  // Create taxonomy
  register_taxonomy(
    'news_category',
    'news',
    array(
      'labels' => array(
        'name' => __( 'Categories' ),
        'singular_name' => __( 'Category' )
      ),
      'hierarchical' => true,
      'query_var' => true,
      'rewrite' => array( 'slug' => 'news/category' )
    )
  );
// Create taxonomy
register_taxonomy(
'news_type',
'news',
array(
'labels' => array(
'name' => __( 'Types' ),
'singular_name' => __( 'Type' )
),
'hierarchical' => true,
'query_var' => true,
'rewrite' => array( 'slug' => 'news/type' )
)
);
}
add_action( 'init', 'create_news_taxonomies' );

This code registers two taxonomies, "news_category" and "news_type," and associates them with our custom post type "news."

Q: How do I filter my custom post type URLs by taxonomy?

A: To filter your custom post type URLs by taxonomy, you'll need to use the add_rewrite_rule function. You'll need to create two rewrite rules, one for each taxonomy:

function add_news_rewrite_rules() {
  add_rewrite_rule(
    '^news/([^/]+)/?$', 'index.php?post_type=news&news_category=$matches[1]', 'top'
  );
add_rewrite_rule(
'^news/([/]+)/([^/]+)/? $&#39;, &#39;index.php?post_type=news&amp;news_category=$ matches[1]&news_type=$matches[2]', 'top'
);
}
add_action( 'init', 'add_news_rewrite_rules' );

This code adds two rewrite rules to our custom post type URLs, one for each taxonomy.

Q: How do I display archive pages for my custom post type?

A: To display archive pages for your custom post type, you'll need to use the get_post_type_archive_link function. You'll need to create two archive pages, one for each taxonomy:

function display_news_archive_pages() {
  $news_category_archive_link = get_post_type_archive_link('news');
  $news_type_archive_link = get_post_type_archive_link('news');
echo '<a href="' . $news_category_archive_link . '">News Category Archive</a>';
echo '<a href="' . $news_type_archive_link . '">News Type Archive</a>';
}

This code displays two archive pages, one for each taxonomy, using the get_post_type_archive_link function.

Q: What are some common issues I might encounter when filtering custom post type URLs by taxonomy?

A: Some common issues you might encounter when filtering custom post type URLs by taxonomy include:

Rewrite rules not being applied: Make sure you've added the add_rewrite_rule function to your theme's functions.php file or a custom plugin.
Taxonomy not being recognized: Make sure you've registered the taxonomy using the register_taxonomy function.
Archive pages not being displayed: Make sure you've used the get_post_type_archive_link function to display the archive pages.

Conclusion

In this article, we've answered some frequently asked questions about filtering custom post type URLs by taxonomy. We've covered topics such as creating custom post types and taxonomies, filtering custom post type URLs by taxonomy, and displaying archive pages for custom post types. With this knowledge, you should be able to filter your custom post type URLs by taxonomy and display archive pages for each taxonomy.

Additional Resources

Example Use Cases

Creating a custom post type for news articles and filtering them by category.
Creating a custom post type for products and filtering them by category and type.
Creating a custom post type for events and filtering them by category and date.

Code Snippets

create_news_post_type function: Creates a custom post type called "news" with the following properties: labels, public, has_archive, and supports.
create_news_taxonomies function: Creates two taxonomies, "news_category" and "news_type," and associates them with our custom post type "news."
add_news_rewrite_rules function: Adds two rewrite rules to our custom post type URLs, one for each taxonomy.
display_news_archive_pages function: Displays two archive pages, one for each taxonomy, using the get_post_type_archive_link function.