Remove parent category from permalink? Basically only have the child category?

I think there used to be an out-dated plugin to do this. Is there any way to do this easily with just a little code? We prefer not to rely on a plugin since that makes us dependent on the developer to keep it up-to-date.

We only have two parent categories we would like to remove for all of their child-category permalinks: “items” and “genres” (so it could be tailored to just removing two category IDs)

I see that there was a solution with the individual posts here, but I don’t think this works with the category permalinks as well, does it ?

Answers:

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Method 1

This code pretty much does the job for this question and another one about removing the /category/ base 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.) Also, it doesn’t change the post permalink. It’s just the category permalink that changes. 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;
}

All methods was sourced from stackoverflow.com or stackexchange.com, is licensed under cc by-sa 2.5, cc by-sa 3.0 and cc by-sa 4.0