wp_create_category deprecated?

Question

Was trying to use this today:

WP Create Category https://codex.wordpress.org/Function_Reference/wp_create_category

Trying that (which I also assume it's only going to add terms to the built in "Categories" taxonomy) throws this error:

Fatal error: Call to undefined function wp_create_category() in /yourwebsite/wp-content/themes/fitt/functions.php on line 123

Though I do see it in /wp-admin/includes/taxonomy.php on line 45:

/**
 * Add a new category to the database if it does not already exist.
 *
 * @since 2.0.0
 *
 * @param int|string $cat_name
 * @param int        $parent
 * @return int|WP_Error
 */
function wp_create_category( $cat_name, $parent = 0 ) {
    if ( $id = category_exists($cat_name, $parent) )
        return $id;

    return wp_insert_category( array('cat_name' => $cat_name, 'category_parent' => $parent) );
}

Has anyone ever seen this before? A function coming up as undefined though it appears to be from both the code and Codex documentation?

Answer 1

You are most probably trying to use wp_create_category() on the front end, which will lead to the fatal error. wp_create_category() is not available on the front end, only backend.

You should hook your function to at least admin_init where wp_create_category() is available.

Just a note, looking at the source code, wp_create_category() uses category_exists() which is quite expensive to run on every page load, so you would want to run this once like on a plugin or theme activation hook