Removing short versions of category archive URL

Question

I'm looking after a site where someone has configured /%category%/%postname% as the Permalink structure.

A side-effect of this seems to be that a category archive will appear both at the usual /category/foo and also /foo.

One downside of this is that it creates a duplicate page. Another is that any "Older posts" link on that second page won't work, since it will point to /foo/page/2 which will return a 404.

Is there any way to disable the /foo version of the page without changing the Permalink structure?

Answer 1

I suppose there's a way to remove the offending rewrite rule from the rules array, maybe on generate_rewrite_rules, which would result in I'm not sure what, maybe a 404, or WordPress would try to redirect to the correct URI.

or, I came up with this bit of code to check for category requests without category in the URL, and 301 redirect them to the version with category. It's a bit crude, but it may work for you.

function wpa_category_requests( $request ){
    if ( ! is_admin()
        && isset( $request->query_vars['category_name'] )
        && ! isset( $request->query_vars['name'] ) ){
        if ( false === strpos( $request->request, 'category' ) ){
            wp_redirect(
                home_url( '/category/' . $request->query_vars['category_name'] . '/' ),
                301
            );
        }
    }
}
add_action( 'parse_request', 'wpa_category_requests' );