Best and Cleanest way to remove /category/ from category permalinks? [duplicate]

Question

Possible Duplicate:
Remove parent category from permalink? Basically only have the child category?

We've seen plugins to do this, and a lot of people with different code modifications. We really would like to achieve this the cleanest and simplest way possible, without worrying about out-dated plugins or causing problems with too many mods.

Answer 1

Not sure how clean or easy this is, but it seems to work. This code pretty much does the job for this question and another one about removing the parent category from the permalinks. Got it from a plugin that does this, and decided to just use the raw code.

So the permalinks only have the lowest child-category listed.

First, we had:

example.com/category/items/books/

and now...

example.com/books

The RSS feeds, however, don't seem to work with this shorter url, and still require the long-form url. (Not sure if there's a fix for that.) Paste the code below into your functions.php file. I'm using Wordpress 3.0+.

// Remove category base
add_filter('category_link', 'no_category_parents',1000,2);
function no_category_parents($catlink, $category_id) {
    $category = &get_category( $category_id );
    if ( is_wp_error( $category ) )
        return $category;
    $category_nicename = $category->slug;

    $catlink = trailingslashit(get_option( 'home' )) . user_trailingslashit( $category_nicename, 'category' );
    return $catlink;
}

// Add our custom category rewrite rules
add_filter('category_rewrite_rules', 'no_category_parents_rewrite_rules');
function no_category_parents_rewrite_rules($category_rewrite) {
    //print_r($category_rewrite); // For Debugging

    $category_rewrite=array();
    $categories=get_categories(array('hide_empty'=>false));
    foreach($categories as $category) {
        $category_nicename = $category->slug;
        $category_rewrite['('.$category_nicename.')/(?:feed/)?(feed|rdf|rss|rss2|atom)/?$'] = 'index.php?category_name=$matches[1]&feed=$matches[2]';
        $category_rewrite['('.$category_nicename.')/page/?([0-9]{1,})/?$'] = 'index.php?category_name=$matches[1]&paged=$matches[2]';
        $category_rewrite['('.$category_nicename.')/?$'] = 'index.php?category_name=$matches[1]';
    }
    // Redirect support from Old Category Base
    global $wp_rewrite;
    $old_base = $wp_rewrite->get_category_permastruct();
    $old_base = str_replace( '%category%', '(.+)', $old_base );
    $old_base = trim($old_base, '/');
    $category_rewrite[$old_base.'$'] = 'index.php?category_redirect=$matches[1]';

    //print_r($category_rewrite); // For Debugging
    return $category_rewrite;
}

// Add 'category_redirect' query variable
add_filter('query_vars', 'no_category_parents_query_vars');
function no_category_parents_query_vars($public_query_vars) {
    $public_query_vars[] = 'category_redirect';
    return $public_query_vars;
}
// Redirect if 'category_redirect' is set
add_filter('request', 'no_category_parents_request');
function no_category_parents_request($query_vars) {
    //print_r($query_vars); // For Debugging
    if(isset($query_vars['category_redirect'])) {
        $catlink = trailingslashit(get_option( 'home' )) . user_trailingslashit( $query_vars['category_redirect'], 'category' );
        status_header(301);
        header("Location: $catlink");
        exit();
    }
    return $query_vars;
}