Adding Categories support to a Custom Post Type in WordPress

When a CPT is manually created in WordPress using register_post_type function it can be linked to the built-in category taxonomy via

'taxonomies' => array( 'category' ),

view raw gistfile1.php hosted with by GitHub

When register_post_type() is defined without support for categories and is coming from a plugin that you can (should) not modify, it is still possible to add categories support to the CPT by adding the following in child theme’s functions.php:

	//* Link e4gf_events CPT to categories taxonomy
	add_action( 'init', 'sk_add_category_taxonomy_to_events' );
	function sk_add_category_taxonomy_to_events() {
	register_taxonomy_for_object_type( 'category', 'e4gf_events' );
	}

view raw functions.php hosted with by GitHub

where e4gf_events is the Post Type Key. This can be easily seen by going to CPT listing page in the backend and looking at the URL.

After this the CPT entry can be assigned Categories just like the standard Posts.

Reference: http://codex.wordpress.org/Function_Reference/register_taxonomy_for_object_type

Before:

After: