How to create custom post types (register_post_type)

“Products,” “Case studies,” “Staff profiles”—a custom post type is how you create a third kind of content alongside posts and pages. Write register_post_type() in functions.php and a dedicated menu appears in the admin screen.

Here’s the minimum that works, ready to copy.

function my_register_post_types() {
  register_post_type('shohin', [
    'label'        => 'Products',
    'public'       => true,
    'has_archive'  => true,
    'menu_icon'    => 'dashicons-cart',
    'supports'     => ['title', 'editor', 'thumbnail', 'excerpt'],
    'show_in_rest' => true,   // edit it in the block editor
  ]);
}
add_action('init', 'my_register_post_types');

That alone adds a “Products” menu to the admin screen and makes /shohin/ the product archive URL.

Why not just mix it into “Posts”?

You could create a “Products” category and put them in Posts, but putting data of different natures in the same box makes management fall apart.

• You want different sort orders and per-page counts for each list
• You want price and stock fields on products only
• You don’t want products mixed into the blog’s RSS feed and archives

Categories sort things within one box; post types add another box entirely—a different scale altogether. If any of the above applies, splitting the post type is the right call.

Argument cheat sheet

Fine-tuning the display names (labels)

label alone gets you most of the way, but when you want to tailor wording like “Add New,” use labels.

'labels' => [
  'name'               => 'Products',
  'singular_name'      => 'Product',
  'add_new_item'       => 'Add product',
  'edit_item'          => 'Edit product',
  'all_items'          => 'All products',
  'search_items'       => 'Search products',
  'not_found'          => 'No products found',
],

Preparing templates

Registering a post type makes dedicated template files available. There are naming rules.

Without them, archive.php then index.php stand in. Get it working on the substitutes first and create dedicated files when you need them—that’s the low-effort path.

Changing the archive URL

Keeping the post type name shohin while the URL is /products/ is a common requirement.

'has_archive' => 'products',
'rewrite'     => ['slug' => 'products', 'with_front' => false],

• Passing a string to has_archive sets the archive URL to that name
• rewrite.slug is the single page’s URL (/products/product-name/)
• with_front => false drops the prefix from your permalink settings (/blog/ and the like)

Choosing a post type name

• Lowercase alphanumerics and underscores, up to 20 characters
• post, page, attachment, revision, nav_menu_item, action, order, theme and others are reserved and can’t be used
• Change it later and all those posts vanish from view (the data remains, but the post type is treated as nonexistent), so decide up front

When in doubt, pick a short site-specific name like shohin. Generic names like item or data risk colliding with plugins, so they’re best avoided.

Adding input fields

Products need fields like price and stock. With ACF (SCF), you can add input fields without code. Set the field group’s “Location” to “Post Type = Products” and the fields appear only in the product editing screen.

If you’re using core custom fields, add 'custom-fields' to supports.

Adding taxonomies too

To classify products by “season” or “brand,” add a custom taxonomy. Reusing the standard categories and tags takes one line.

'taxonomies' => ['category', 'post_tag'],

Outputting the list in a template

To line products up on the front page, fetch them with WP_Query. The key is specifying post_type.

<?php
$items = new WP_Query([
  'post_type'      => 'shohin',
  'posts_per_page' => 6,
]);
?>
<?php while ($items->have_posts()) : $items->the_post(); ?>
  <a href="<?php the_permalink(); ?>"><?php the_title(); ?></a>
<?php endwhile; ?>
<?php wp_reset_postdata(); ?>

functions.php or a plugin?

• The theme’s functions.php—easy. But change themes and the post type disappears (the data remains, it just becomes invisible in the admin screen)
• A dedicated plugin (one file in wp-content/plugins/my-post-types/)—survives theme changes. Suited to long-running sites

There are plugins that let you create these from the admin screen, but writing code means you can carry the same setup to another site. As a learning exercise too, writing it in code first is what I’d recommend.

Summary

1. Just run register_post_type() on the init hook in functions.php
2. has_archive sets the archive, supports sets the editing panels, show_in_rest enables the block editor
3. Templates are archive-<name>.php / single-<name>.php. Without them, existing files stand in
4. On a 404, re-save the permalink settings. Decide the post type name up front and don’t change it

Once you can split content by type, you can design “one WordPress managing many kinds of content.”