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* @package WPSEO\Frontend
* This code handles the category rewrites.
public function __construct() {
add_filter( 'query_vars', [ $this, 'query_vars' ] );
add_filter( 'term_link', [ $this, 'no_category_base' ], 10, 3 );
add_filter( 'request', [ $this, 'request' ] );
add_filter( 'category_rewrite_rules', [ $this, 'category_rewrite_rules' ] );
add_action( 'created_category', [ $this, 'schedule_flush' ] );
add_action( 'edited_category', [ $this, 'schedule_flush' ] );
add_action( 'delete_category', [ $this, 'schedule_flush' ] );
* Trigger a rewrite_rule flush on shutdown.
public function schedule_flush() {
add_action( 'shutdown', 'flush_rewrite_rules' );
* Override the category link to remove the category base.
* @param string $link Term link, overridden by the function for categories.
* @param WP_Term $term Unused, term object.
* @param string $taxonomy Taxonomy slug.
public function no_category_base( $link, $term, $taxonomy ) {
if ( $taxonomy !== 'category' ) {
$category_base = get_option( 'category_base' );
if ( empty( $category_base ) ) {
$category_base = 'category';
* Remove initial slash, if there is one (we remove the trailing slash
* in the regex replacement and don't want to end up short a slash).
if ( substr( $category_base, 0, 1 ) === '/' ) {
$category_base = substr( $category_base, 1 );
return preg_replace( '`' . preg_quote( $category_base, '`' ) . '`u', '', $link, 1 );
* Update the query vars with the redirect var when stripcategorybase is active.
* @param array<string> $query_vars Main query vars to filter.
* @return array<string> The query vars.
public function query_vars( $query_vars ) {
if ( WPSEO_Options::get( 'stripcategorybase' ) === true ) {
$query_vars[] = 'wpseo_category_redirect';
* Checks whether the redirect needs to be created.
* @param array<string> $query_vars Query vars to check for existence of redirect var.
* @return array<string> The query vars.
public function request( $query_vars ) {
if ( ! isset( $query_vars['wpseo_category_redirect'] ) ) {
$this->redirect( $query_vars['wpseo_category_redirect'] );
* This function taken and only slightly adapted from WP No Category Base plugin by Saurabh Gupta.
* @return array<string> The category rewrite rules.
public function category_rewrite_rules() {
$taxonomy = get_taxonomy( 'category' );
$permalink_structure = get_option( 'permalink_structure' );
if ( strpos( $permalink_structure, '/blog/' ) === 0 ) {
if ( ( is_multisite() && ! is_subdomain_install() ) || is_main_site() || is_main_network() ) {
$categories = get_categories( [ 'hide_empty' => false ] );
if ( is_array( $categories ) && $categories !== [] ) {
foreach ( $categories as $category ) {
$category_nicename = $category->slug;
if ( $category->parent === $category->cat_ID ) {
elseif ( $taxonomy->rewrite['hierarchical'] !== false && $category->parent !== 0 ) {
$parents = get_category_parents( $category->parent, false, '/', true );
if ( ! is_wp_error( $parents ) ) {
$category_nicename = $parents . $category_nicename;
$category_rewrite = $this->add_category_rewrites( $category_rewrite, $category_nicename, $blog_prefix, $wp_rewrite->pagination_base );
// Adds rules for the uppercase encoded URIs.
$category_nicename_filtered = $this->convert_encoded_to_upper( $category_nicename );
if ( $category_nicename_filtered !== $category_nicename ) {
$category_rewrite = $this->add_category_rewrites( $category_rewrite, $category_nicename_filtered, $blog_prefix, $wp_rewrite->pagination_base );
unset( $categories, $category, $category_nicename, $category_nicename_filtered );
// Redirect support from Old Category Base.
$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?wpseo_category_redirect=$matches[1]';
return $category_rewrite;
* Adds required category rewrites rules.
* @param array<string> $rewrites The current set of rules.
* @param string $category_name Category nicename.
* @param string $blog_prefix Multisite blog prefix.
* @param string $pagination_base WP_Query pagination base.
* @return array<string> The added set of rules.
protected function add_category_rewrites( $rewrites, $category_name, $blog_prefix, $pagination_base ) {
$rewrite_name = $blog_prefix . '(' . $category_name . ')';
$feed_regex = '(' . implode( '|', $wp_rewrite->feeds ) . ')';
$rewrites[ $rewrite_name . '/(?:feed/)?' . $feed_regex . '/?$' ] = 'index.php?category_name=$matches[1]&feed=$matches[2]';
$rewrites[ $rewrite_name . '/' . $pagination_base . '/?([0-9]{1,})/?$' ] = 'index.php?category_name=$matches[1]&paged=$matches[2]';
$rewrites[ $rewrite_name . '/?$' ] = 'index.php?category_name=$matches[1]';
* Walks through category nicename and convert encoded parts
* into uppercase using $this->encode_to_upper().
* @param string $name The encoded category URI string.
* @return string The convered URI string.
protected function convert_encoded_to_upper( $name ) {
// Checks if name has any encoding in it.
if ( strpos( $name, '%' ) === false ) {
$names = explode( '/', $name );
$names = array_map( [ $this, 'encode_to_upper' ], $names );
return implode( '/', $names );
* Converts the encoded URI string to uppercase.
* @param string $encoded The encoded string.
* @return string The uppercased string.
public function encode_to_upper( $encoded ) {
if ( strpos( $encoded, '%' ) === false ) {
return strtoupper( $encoded );
* Redirect the "old" category URL to the new one.
* @param string $category_redirect The category page to redirect to.
protected function redirect( $category_redirect ) {
$catlink = trailingslashit( get_option( 'home' ) ) . user_trailingslashit( $category_redirect, 'category' );
wp_safe_redirect( $catlink, 301, 'Yoast SEO' );
It is recommended that you Edit text format, this type of Fix handles quite a lot in one request
