Modify functions.php to add a term 'uses-theme' set to theme name on post save

Question

I need to automatically (without anything visible to the user in the UI and without user intervention) 'mark' a post in a sub-blog with the theme it was set to when the user posted.

As I understand it I have to use wp_insert_term() once to insert this new term 'uses-theme' into the terms table in the database.

Then I have to add an action containing wp_set_post_terms() (with the value of get_current_theme()), to some core function that is executed when a post is created or saved.

I don't have access to the core .php files, so I'm looking for some way of adding this to the functions.php.

If it's easier to automatically tag or categorize, I will do that. I just don't know how to hook it in.

UPDATE: I just realized I get the blogid in the post meta. If I could look up the stylesheet_directory or similar "bloginfo" field from the database, the problem would be solved. But I'm looking at the blogs table, and it doesn't have those bloginfo fields - and get_bloginfo() only returns info about the CURRENT blog.

If I knew how to look up stylesheet information from the blog id, I would be home! How?

Answer 1

I would create custom post meta for this data, as it seems the most logical. It should be easy to implement, since you don't need to expose this custom meta data to the UI; just add a callback to save_post.

You can use wp_get_theme() to retrieve information about the current Theme. This function returns an instance of the WP_Theme object.

function wpse76752_add_post_meta() {
    global $post;
    $current_theme = wp_get_theme();
    update_post_meta( $post->ID, '_current_theme', $current_theme->Name );
}
add_action( 'save_post', 'wpse76752_add_post_meta' );

Note that I prefaced the custom post meta key with an underscore. This prevents the meta key from being listed in the "custom fields" dropdown in the Edit Post screen. (Basically, it makes it an "internal" post meta key, that is hidden from the UI unless you explicitly expose it.)