Had a client ask me the other day if the existing name of the Custom Post Type in question could be changed as the url or taxonomy. So how do you Change Custom Post type Name and Taxonomy of existing Custom Post Type? Well there are a few steps you need to take to do this without blowing up your website.

Custom Post Type Setup

As with most if not all custom post type setups you have the option to create posts under that custom post type. The name of that post and slug can be adjusted, but the name for the group it is under cannot be changed. So in our case the name module or plural modules cannot be changed in the backend. To do that you have to change things in the database and in the code to load things properly.

Backup

Backup your site’s database and theme files before you get started. You will be making theme file changes as well as do a database update. So make sure you can revert when shit hits the fence. Always better to the safe than sorry, right?

Change Custom Post Type Name in Database

To update the Custom Post Type name we would have to run the following in the database:

UPDATE `wp_posts`
SET 
 # Update the post_type column
 `post_type` = REPLACE(`post_type`,'name_of_old_post_type','name_of_new_post_type'),
 # Update the urls
 `guid` = REPLACE(`guid`,'name_of_old_post_type','name_of_new_post_type')
WHERE `post_type` = 'name_of_old_post_type'

NB See SO thread on something similar here.

You might though just do a simple:

UPDATE `wp_posts` SET `post_type` = '' WHERE `post_type` = '';

without replacing the GUID might suffice as well. Then you just need to update the permalinks after that has been changed as well as the taxonomy here below. With this query you basically update the name of the custom post type without changed the GUID. It is simple and quick.

Change Taxonomy Name in Database

To update the url or taxonomy used by the Custom Post Type you will have to to do the following

UPDATE `wp_term_taxonomy` SET `taxonomy` = '' WHERE `taxonomy` = '';

See also WordPress Stack Exchange thread

Post Meta

If you have stored any references to this post type within wp_postmeta within serialized arrays you cannot simply do a search and replace as they replaced strings need to be of the same length or things won’t work anymore. There are scripts and plugins out there that can help with this though. Here is a Better Search and Replace plugin and there is of course wp-cli search and replace that does all this taking care of serialized data as well.

Permalink Update

Do not forget to update the permalinks after these changes under settings > permalinks. Otherwise your existing custom post type posts won’t load anymore and neither will the taxonomy they are under. But hey, this is not hard to take care of now is it?

Theme Changes

You’ll need to update any references to this post type in your code. So references to the old custom post type and taxonomy in template files, functions.php and so on. And this could take some time. Especially if it wasn’t you who created the theme in the first place. And that was the case in our case. In the end we postponed this big change as a new theme change was coming up. Once that is done we will get back to this possible upgrade.