Using WordPress ‘redirect_canonical()’ PHP function

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The redirect_canonical() WordPress PHP function redirects incoming links to the proper URL based on the site URL, improving SEO by avoiding duplicate content penalties.

Usage

To use the redirect_canonical() function, you can create a custom function that checks for specific conditions and then hooks it to the ‘template_redirect’ action.

function custom_redirect_canonical() {
  // Your conditions and logic here
}
add_action('template_redirect', 'custom_redirect_canonical');

Parameters

  • $requested_url (string) – Optional. The URL that was requested, used to figure if redirect is needed. Default: null
  • $do_redirect (bool) – Optional. Redirect to the new URL. Default: true

More information

See WordPress Developer Resources: redirect_canonical

Examples

Create 301 redirects for canonical URLs

This example creates 301 redirects for single posts to ensure the correct URL is used:

function wpdocs_redirect_can() {
  if (is_single()) {
    global $wp;
    $wp->parse_request();
    $current_url = trim(home_url($wp->request), '/');
    $redirect = get_permalink();
    $surl = trim($redirect, '/');

    if ($current_url !== $surl) {
      wp_redirect($redirect, 301);
      exit;
    }
  }
}
add_action('template_redirect', 'wpdocs_redirect_can');

Remove redirect for custom taxonomy with a specific query variable

This example removes the canonical redirect for a custom taxonomy ‘event_category’ when the ‘year’ query variable is present:

add_filter('redirect_canonical', 'pick_event_year_redirect', 10);

function pick_event_year_redirect($redirect_url) {
  if (is_tax('event_category') && is_year()) {
    return '';
  }
  return $redirect_url;
}

Redirect non-www to www

This example redirects non-www URLs to www URLs for better SEO:

function force_www_redirect() {
  if (strpos($_SERVER['HTTP_HOST'], 'www.') === false) {
    wp_redirect('https://www.' . $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'], 301);
    exit;
  }
}
add_action('template_redirect', 'force_www_redirect');

Redirect posts to a custom URL

This example redirects all posts to a custom URL based on the post ID:

function redirect_posts_to_custom_url() {
  if (is_single()) {
    $post_id = get_the_ID();
    $new_url = home_url('/custom-url/') . $post_id;
    wp_redirect($new_url, 301);
    exit;
  }
}
add_action('template_redirect', 'redirect_posts_to_custom_url');

Redirect a specific page to another URL

This example redirects a specific page with the slug ‘old-page’ to another URL:

function redirect_old_page_to_new_url() {
  if (is_page('old-page')) {
    $new_url = 'https://example.com/new-page/';
    wp_redirect($new_url, 301);
    exit;
  }
}
add_action('template_redirect', 'redirect_old_page_to_new_url');