redirect_canonical()
云策文档标注
概述
redirect_canonical() 是 WordPress 的核心函数，用于处理 URL 规范化重定向，以解决 SEO 中的重复内容问题。它基于站点 URL 将传入链接重定向到正确的 URL，并处理多种场景如 404 页面、查询参数清理等。
关键要点
- 主要功能：防止搜索引擎因重复内容（如 www 与非 www 版本）而惩罚站点，通过 301 重定向统一 URL。
- 不重定向的场景：包括 feeds、trackbacks、搜索、admin 页面、POST 请求、预览页面、IIS 7+ 非漂亮链接等。
- 处理 404 页面：尝试根据查询变量猜测正确链接，如通过 post ID、日期参数等。
- 参数：$requested_url（可选，请求的 URL）和 $do_redirect（可选，是否执行重定向，默认为 true）。
- 返回值：如果需要重定向，返回 URL 字符串；否则返回 void。
- 相关 Hook：apply_filters('redirect_canonical', $redirect_url, $requested_url) 可用于过滤重定向 URL。
代码示例
function redirect_canonical( $requested_url = null, $do_redirect = true ) {
// 函数实现代码（此处省略详细内容，参考文档正文）
if ( $do_redirect ) {
wp_redirect( $redirect_url, 301 );
exit;
} else {
return $redirect_url;
}
}注意事项
- 函数内部使用多个条件检查（如 is_admin()、is_search()）来决定是否跳过重定向。
- 支持通过 apply_filters('redirect_canonical') 自定义重定向逻辑，开发者可添加过滤器修改行为。
- 在开发插件或主题时，应避免直接调用内部函数如 _remove_qs_args_if_not_in_url()。
原文内容
Redirects incoming links to the proper URL based on the site url.
Description
Search engines consider www.somedomain.com and somedomain.com to be two different URLs when they both go to the same location. This SEO enhancement prevents penalty for duplicate content by redirecting all incoming links to one or the other.
Prevents redirection for feeds, trackbacks, searches, and admin URLs. Does not redirect on non-pretty-permalink-supporting IIS 7+, page/post previews, WP admin, Trackbacks, robots.txt, favicon.ico, searches, or on POST requests.
Will also attempt to find the correct link when a user enters a URL that does not exist based on exact WordPress query. Will instead try to parse the URL or query in an attempt to figure the correct page to go to.
Parameters
$requested_urlstringoptional-
The URL that was requested, used to figure if redirect is needed.
Default:
null $do_redirectbooloptional-
Redirect to the new URL.
Default:
true
Source
function redirect_canonical( $requested_url = null, $do_redirect = true ) {
global $wp_rewrite, $is_IIS, $wp_query, $wpdb, $wp;
if ( isset( $_SERVER['REQUEST_METHOD'] ) && ! in_array( strtoupper( $_SERVER['REQUEST_METHOD'] ), array( 'GET', 'HEAD' ), true ) ) {
return;
}
/*
* If we're not in wp-admin and the post has been published and preview nonce
* is non-existent or invalid then no need for preview in query.
*/
if ( is_preview() && get_query_var( 'p' ) && 'publish' === get_post_status( get_query_var( 'p' ) ) ) {
if ( ! isset( $_GET['preview_id'] )
|| ! isset( $_GET['preview_nonce'] )
|| ! wp_verify_nonce( $_GET['preview_nonce'], 'post_preview_' . (int) $_GET['preview_id'] )
) {
$wp_query->is_preview = false;
}
}
if ( is_admin() || is_search() || is_preview() || is_trackback() || is_favicon()
|| ( $is_IIS && ! iis7_supports_permalinks() )
) {
return;
}
if ( ! $requested_url && isset( $_SERVER['HTTP_HOST'] ) ) {
// Build the URL in the address bar.
$requested_url = is_ssl() ? 'https://' : 'http://';
$requested_url .= $_SERVER['HTTP_HOST'];
$requested_url .= $_SERVER['REQUEST_URI'];
}
$original = parse_url( $requested_url );
if ( false === $original ) {
return;
}
// Notice fixing.
$original += array(
'host' => '',
'path' => '',
'query' => '',
'scheme' => '',
);
$redirect = $original;
$redirect_url = false;
$redirect_obj = false;
/*
* If the original URL ended with non-breaking spaces, they were almost
* certainly inserted by accident. Let's remove them, so the reader doesn't
* see a 404 error with no obvious cause.
*/
$redirect['path'] = preg_replace( '|(%C2%A0)+$|i', '', $redirect['path'] );
// It's not a preview, so remove it from URL.
if ( get_query_var( 'preview' ) ) {
$redirect['query'] = remove_query_arg( 'preview', $redirect['query'] );
}
$post_id = get_query_var( 'p' );
if ( is_feed() && $post_id ) {
$redirect_url = get_post_comments_feed_link( $post_id, get_query_var( 'feed' ) );
$redirect_obj = get_post( $post_id );
if ( $redirect_url ) {
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type', 'feed' ),
$redirect_url
);
$redirect['path'] = parse_url( $redirect_url, PHP_URL_PATH );
}
}
if ( is_singular() && $wp_query->post_count < 1 && $post_id ) {
$vars = $wpdb->get_results( $wpdb->prepare( "SELECT post_type, post_parent FROM $wpdb->posts WHERE ID = %d", $post_id ) );
if ( ! empty( $vars[0] ) ) {
$vars = $vars[0];
if ( 'revision' === $vars->post_type && $vars->post_parent > 0 ) {
$post_id = $vars->post_parent;
}
$redirect_url = get_permalink( $post_id );
$redirect_obj = get_post( $post_id );
if ( $redirect_url ) {
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ),
$redirect_url
);
}
}
}
// These tests give us a WP-generated permalink.
if ( is_404() ) {
// Redirect ?page_id, ?p=, ?attachment_id= to their respective URLs.
$post_id = max( get_query_var( 'p' ), get_query_var( 'page_id' ), get_query_var( 'attachment_id' ) );
$redirect_post = $post_id ? get_post( $post_id ) : false;
if ( $redirect_post ) {
$post_type_obj = get_post_type_object( $redirect_post->post_type );
if ( $post_type_obj && $post_type_obj->public && 'auto-draft' !== $redirect_post->post_status ) {
$redirect_url = get_permalink( $redirect_post );
$redirect_obj = get_post( $redirect_post );
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ),
$redirect_url
);
}
}
$year = get_query_var( 'year' );
$month = get_query_var( 'monthnum' );
$day = get_query_var( 'day' );
if ( $year && $month && $day ) {
$date = sprintf( '%04d-%02d-%02d', $year, $month, $day );
if ( ! wp_checkdate( $month, $day, $year, $date ) ) {
$redirect_url = get_month_link( $year, $month );
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'year', 'monthnum', 'day' ),
$redirect_url
);
}
} elseif ( $year && $month && $month > 12 ) {
$redirect_url = get_year_link( $year );
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'year', 'monthnum' ),
$redirect_url
);
}
// Strip off non-existing <!--nextpage--> links from single posts or pages.
if ( get_query_var( 'page' ) ) {
$post_id = 0;
if ( $wp_query->queried_object instanceof WP_Post ) {
$post_id = $wp_query->queried_object->ID;
} elseif ( $wp_query->post ) {
$post_id = $wp_query->post->ID;
}
if ( $post_id ) {
$redirect_url = get_permalink( $post_id );
$redirect_obj = get_post( $post_id );
$redirect['path'] = rtrim( $redirect['path'], (int) get_query_var( 'page' ) . '/' );
$redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
}
}
if ( ! $redirect_url ) {
$redirect_url = redirect_guess_404_permalink();
if ( $redirect_url ) {
$redirect['query'] = _remove_qs_args_if_not_in_url(
$redirect['query'],
array( 'page', 'feed', 'p', 'page_id', 'attachment_id', 'pagename', 'name', 'post_type' ),
$redirect_url
);
}
}
} elseif ( is_object( $wp_rewrite ) && $wp_rewrite->using_permalinks() ) {
// Rewriting of old ?p=X, ?m=2004, ?m=200401, ?m=20040101.
if ( is_attachment()
&& ! array_diff( array_keys( $wp->query_vars ), array( 'attachment', 'attachment_id' ) )
&& ! $redirect_url
) {
if ( ! empty( $_GET['attachment_id'] ) ) {
$redirect_url = get_attachment_link( get_query_var( 'attachment_id' ) );
$redirect_obj = get_post( get_query_var( 'attachment_id' ) );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'attachment_id', $redirect['query'] );
}
} else {
$redirect_url = get_attachment_link();
$redirect_obj = get_post();
}
} elseif ( is_single() && ! empty( $_GET['p'] ) && ! $redirect_url ) {
$redirect_url = get_permalink( get_query_var( 'p' ) );
$redirect_obj = get_post( get_query_var( 'p' ) );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( array( 'p', 'post_type' ), $redirect['query'] );
}
} elseif ( is_single() && ! empty( $_GET['name'] ) && ! $redirect_url ) {
$redirect_url = get_permalink( $wp_query->get_queried_object_id() );
$redirect_obj = get_post( $wp_query->get_queried_object_id() );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'name', $redirect['query'] );
}
} elseif ( is_page() && ! empty( $_GET['page_id'] ) && ! $redirect_url ) {
$redirect_url = get_permalink( get_query_var( 'page_id' ) );
$redirect_obj = get_post( get_query_var( 'page_id' ) );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'page_id', $redirect['query'] );
}
} elseif ( is_page() && ! is_feed() && ! $redirect_url
&& 'page' === get_option( 'show_on_front' ) && get_queried_object_id() === (int) get_option( 'page_on_front' )
) {
$redirect_url = home_url( '/' );
} elseif ( is_home() && ! empty( $_GET['page_id'] ) && ! $redirect_url
&& 'page' === get_option( 'show_on_front' ) && get_query_var( 'page_id' ) === (int) get_option( 'page_for_posts' )
) {
$redirect_url = get_permalink( get_option( 'page_for_posts' ) );
$redirect_obj = get_post( get_option( 'page_for_posts' ) );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'page_id', $redirect['query'] );
}
} elseif ( ! empty( $_GET['m'] ) && ( is_year() || is_month() || is_day() ) ) {
$m = get_query_var( 'm' );
switch ( strlen( $m ) ) {
case 4: // Yearly.
$redirect_url = get_year_link( $m );
break;
case 6: // Monthly.
$redirect_url = get_month_link( substr( $m, 0, 4 ), substr( $m, 4, 2 ) );
break;
case 8: // Daily.
$redirect_url = get_day_link( substr( $m, 0, 4 ), substr( $m, 4, 2 ), substr( $m, 6, 2 ) );
break;
}
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'm', $redirect['query'] );
}
// Now moving on to non ?m=X year/month/day links.
} elseif ( is_date() ) {
$year = get_query_var( 'year' );
$month = get_query_var( 'monthnum' );
$day = get_query_var( 'day' );
if ( is_day() && $year && $month && ! empty( $_GET['day'] ) ) {
$redirect_url = get_day_link( $year, $month, $day );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( array( 'year', 'monthnum', 'day' ), $redirect['query'] );
}
} elseif ( is_month() && $year && ! empty( $_GET['monthnum'] ) ) {
$redirect_url = get_month_link( $year, $month );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( array( 'year', 'monthnum' ), $redirect['query'] );
}
} elseif ( is_year() && ! empty( $_GET['year'] ) ) {
$redirect_url = get_year_link( $year );
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'year', $redirect['query'] );
}
}
} elseif ( is_author() && ! empty( $_GET['author'] )
&& is_string( $_GET['author'] ) && preg_match( '|^[0-9]+$|', $_GET['author'] )
) {
$author = get_userdata( get_query_var( 'author' ) );
if ( false !== $author
&& $wpdb->get_var( $wpdb->prepare( "SELECT ID FROM $wpdb->posts WHERE $wpdb->posts.post_author = %d AND $wpdb->posts.post_status = 'publish' LIMIT 1", $author->ID ) )
) {
$redirect_url = get_author_posts_url( $author->ID, $author->user_nicename );
$redirect_obj = $author;
if ( $redirect_url ) {
$redirect['query'] = remove_query_arg( 'author', $redirect['query'] );
}
}
} elseif ( is_category() || is_tag() || is_tax() ) { // Terms (tags/categories).
$term_count = 0;
foreach ( $wp_query->tax_query->queried_terms as $tax_query ) {
if ( isset( $tax_query['terms'] ) && is_countable( $tax_query['terms'] ) ) {
$term_count += count( $tax_query['terms'] );
}
}
$obj = $wp_query->get_queried_object();
if ( $term_count <= 1 && ! empty( $obj->term_id ) ) {
$tax_url = get_term_link( (int) $obj->term_id, $obj->taxonomy );
if ( $tax_url && ! is_wp_error( $tax_url ) ) {
if ( ! empty( $redirect['query'] ) ) {
// Strip taxonomy query vars off the URL.
$qv_remove = array( 'term', 'taxonomy' );
if ( is_category() ) {
$qv_remove[] = 'category_name';
$qv_remove[] = 'cat';
} elseif ( is_tag() ) {
$qv_remove[] = 'tag';
$qv_remove[] = 'tag_id';
} else {
// Custom taxonomies will have a custom query var, remove those too.
$tax_obj = get_taxonomy( $obj->taxonomy );
if ( false !== $tax_obj->query_var ) {
$qv_remove[] = $tax_obj->query_var;
}
}
$rewrite_vars = array_diff( array_keys( $wp_query->query ), array_keys( $_GET ) );
// Check to see if all the query vars are coming from the rewrite, none are set via $_GET.
if ( ! array_diff( $rewrite_vars, array_keys( $_GET ) ) ) {
// Remove all of the per-tax query vars.
$redirect['query'] = remove_query_arg( $qv_remove, $redirect['query'] );
// Create the destination URL for this taxonomy.
$tax_url = parse_url( $tax_url );
if ( ! empty( $tax_url['query'] ) ) {
// Taxonomy accessible via ?taxonomy=...&term;=... or any custom query var.
parse_str( $tax_url['query'], $query_vars );
$redirect['query'] = add_query_arg( $query_vars, $redirect['query'] );
} else {
// Taxonomy is accessible via a "pretty URL".
$redirect['path'] = $tax_url['path'];
}
} else {
// Some query vars are set via $_GET. Unset those from $_GET that exist via the rewrite.
foreach ( $qv_remove as $_qv ) {
if ( isset( $rewrite_vars[ $_qv ] ) ) {
$redirect['query'] = remove_query_arg( $_qv, $redirect['query'] );
}
}
}
}
}
}
} elseif ( is_single() && str_contains( $wp_rewrite->permalink_structure, '%category%' ) ) {
$category_name = get_query_var( 'category_name' );
if ( $category_name ) {
$category = get_category_by_path( $category_name );
if ( ! $category || is_wp_error( $category )
|| ! has_term( $category->term_id, 'category', $wp_query->get_queried_object_id() )
) {
$redirect_url = get_permalink( $wp_query->get_queried_object_id() );
$redirect_obj = get_post( $wp_query->get_queried_object_id() );
}
}
}
// Post paging.
if ( is_singular() && get_query_var( 'page' ) ) {
$page = get_query_var( 'page' );
if ( ! $redirect_url ) {
$redirect_url = get_permalink( get_queried_object_id() );
$redirect_obj = get_post( get_queried_object_id() );
}
if ( $page > 1 ) {
$redirect_url = trailingslashit( $redirect_url );
if ( is_front_page() ) {
$redirect_url .= user_trailingslashit( "$wp_rewrite->pagination_base/$page", 'paged' );
} else {
$redirect_url .= user_trailingslashit( $page, 'single_paged' );
}
}
$redirect['query'] = remove_query_arg( 'page', $redirect['query'] );
}
if ( get_query_var( 'sitemap' ) ) {
$redirect_url = get_sitemap_url( get_query_var( 'sitemap' ), get_query_var( 'sitemap-subtype' ), get_query_var( 'paged' ) );
$redirect['query'] = remove_query_arg( array( 'sitemap', 'sitemap-subtype', 'paged' ), $redirect['query'] );
} elseif ( get_query_var( 'paged' ) || is_feed() || get_query_var( 'cpage' ) ) {
// Paging and feeds.
$paged = get_query_var( 'paged' );
$feed = get_query_var( 'feed' );
$cpage = get_query_var( 'cpage' );
while ( preg_match( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", $redirect['path'] )
|| preg_match( '#/(comments/?)?(feed|rss2?|rdf|atom)(/+)?$#', $redirect['path'] )
|| preg_match( "#/{$wp_rewrite->comments_pagination_base}-[0-9]+(/+)?$#", $redirect['path'] )
) {
// Strip off any existing paging.
$redirect['path'] = preg_replace( "#/$wp_rewrite->pagination_base/?[0-9]+?(/+)?$#", '/', $redirect['path'] );
// Strip off feed endings.
$redirect['path'] = preg_replace( '#/(comments/?)?(feed|rss2?|rdf|atom)(/+|$)#', '/', $redirect['path'] );
// Strip off any existing comment paging.
$redirect['path'] = preg_replace( "#/{$wp_rewrite->comments_pagination_base}-[0-9]+?(/+)?$#", '/', $redirect['path'] );
}
$addl_path = '';
$default_feed = get_default_feed();
if ( is_feed() && in_array( $feed, $wp_rewrite->feeds, true ) ) {
$addl_path = ! empty( $addl_path ) ? trailingslashit( $addl_path ) : '';
if ( ! is_singular() && get_query_var( 'withcomments' ) ) {
$addl_path .= 'comments/';
}
if ( ( 'rss' === $default_feed && 'feed' === $feed ) || 'rss' === $feed ) {
$format = ( 'rss2' === $default_feed ) ? '' : 'rss2';
} else {
$format = ( $default_feed === $feed || 'feed' === $feed ) ? '' : $feed;
}
$addl_path .= user_trailingslashit( 'feed/' . $format, 'feed' );
$redirect['query'] = remove_query_arg( 'feed', $redirect['query'] );
} elseif ( is_feed() && 'old' === $feed ) {
$old_feed_files = array(
'wp-atom.php' => 'atom',
'wp-commentsrss2.php' => 'comments_rss2',
'wp-feed.php' => $default_feed,
'wp-rdf.php' => 'rdf',
'wp-rss.php' => 'rss2',
'wp-rss2.php' => 'rss2',
);
if ( isset( $old_feed_files[ basename( $redirect['path'] ) ] ) ) {
$redirect_url = get_feed_link( $old_feed_files[ basename( $redirect['path'] ) ] );
wp_redirect( $redirect_url, 301 );
die();
}
}
if ( $paged > 0 ) {
$redirect['query'] = remove_query_arg( 'paged', $redirect['query'] );
if ( ! is_feed() ) {
if ( ! is_single() ) {
$addl_path = ! empty( $addl_path ) ? trailingslashit( $addl_path ) : '';
if ( $paged > 1 ) {
$addl_path .= user_trailingslashit( "$wp_rewrite->pagination_base/$paged", 'paged' );
}
}
} elseif ( $paged > 1 ) {
$redirect['query'] = add_query_arg( 'paged', $paged, $redirect['query'] );
}
}
$default_comments_page = get_option( 'default_comments_page' );
if ( get_option( 'page_comments' )
&& ( 'newest' === $default_comments_page && $cpage > 0
|| 'newest' !== $default_comments_page && $cpage > 1 )
) {
$addl_path = ( ! empty( $addl_path ) ? trailingslashit( $addl_path ) : '' );
$addl_path .= user_trailingslashit( $wp_rewrite->comments_pagination_base . '-' . $cpage, 'commentpaged' );
$redirect['query'] = remove_query_arg( 'cpage', $redirect['query'] );
}
// Strip off trailing /index.php/.
$redirect['path'] = preg_replace( '|/' . preg_quote( $wp_rewrite->index, '|' ) . '/?$|', '/', $redirect['path'] );
$redirect['path'] = user_trailingslashit( $redirect['path'] );
if ( ! empty( $addl_path )
&& $wp_rewrite->using_index_permalinks()
&& ! str_contains( $redirect['path'], '/' . $wp_rewrite->index . '/' )
) {
$redirect['path'] = trailingslashit( $redirect['path'] ) . $wp_rewrite->index . '/';
}
if ( ! empty( $addl_path ) ) {
$redirect['path'] = trailingslashit( $redirect['path'] ) . $addl_path;
}
$redirect_url = $redirect['scheme'] . '://' . $redirect['host'] . $redirect['path'];
}
if ( 'wp-register.php' === basename( $redirect['path'] ) ) {
if ( is_multisite() ) {
/** This filter is documented in wp-login.php */
$redirect_url = apply_filters( 'wp_signup_location', network_site_url( 'wp-signup.php' ) );
} else {
$redirect_url = wp_registration_url();
}
wp_redirect( $redirect_url, 301 );
die();
}
}
$is_attachment_redirect = false;
if ( is_attachment() && ! get_option( 'wp_attachment_pages_enabled' ) ) {
$attachment_id = get_query_var( 'attachment_id' );
$attachment_post = get_post( $attachment_id );
$attachment_parent_id = $attachment_post ? $attachment_post->post_parent : 0;
$attachment_url = wp_get_attachment_url( $attachment_id );
if ( $attachment_url !== $redirect_url ) {
/*
* If an attachment is attached to a post, it inherits the parent post's status.
* Fetch the parent post to check its status later.
*/
if ( $attachment_parent_id ) {
$redirect_obj = get_post( $attachment_parent_id );
}
$redirect_url = $attachment_url;
}
$is_attachment_redirect = true;
}
$redirect['query'] = preg_replace( '#^??&*?#', '', $redirect['query'] );
// Tack on any additional query vars.
if ( $redirect_url && ! empty( $redirect['query'] ) ) {
parse_str( $redirect['query'], $_parsed_query );
$redirect = parse_url( $redirect_url );
if ( ! empty( $_parsed_query['name'] ) && ! empty( $redirect['query'] ) ) {
parse_str( $redirect['query'], $_parsed_redirect_query );
if ( empty( $_parsed_redirect_query['name'] ) ) {
unset( $_parsed_query['name'] );
}
}
$_parsed_query = array_combine(
rawurlencode_deep( array_keys( $_parsed_query ) ),
rawurlencode_deep( array_values( $_parsed_query ) )
);
$redirect_url = add_query_arg( $_parsed_query, $redirect_url );
}
if ( $redirect_url ) {
$redirect = parse_url( $redirect_url );
}
// www.example.com vs. example.com
$user_home = parse_url( home_url() );
if ( ! empty( $user_home['host'] ) ) {
$redirect['host'] = $user_home['host'];
}
if ( empty( $user_home['path'] ) ) {
$user_home['path'] = '/';
}
// Handle ports.
if ( ! empty( $user_home['port'] ) ) {
$redirect['port'] = $user_home['port'];
} else {
unset( $redirect['port'] );
}
// Notice prevention after new parse_url( $redirect_url ) calls
$redirect += array(
'host' => '',
'path' => '',
'query' => '',
'scheme' => '',
);
// Trailing /index.php.
$redirect['path'] = preg_replace( '|/' . preg_quote( $wp_rewrite->index, '|' ) . '/*?$|', '/', $redirect['path'] );
$punctuation_pattern = implode(
'|',
array_map(
'preg_quote',
array(
' ',
'%20', // Space.
'!',
'%21', // Exclamation mark.
'"',
'%22', // Double quote.
"'",
'%27', // Single quote.
'(',
'%28', // Opening bracket.
')',
'%29', // Closing bracket.
',',
'%2C', // Comma.
'.',
'%2E', // Period.
';',
'%3B', // Semicolon.
'{',
'%7B', // Opening curly bracket.
'}',
'%7D', // Closing curly bracket.
'%E2%80%9C', // Opening curly quote.
'%E2%80%9D', // Closing curly quote.
)
)
);
// Remove trailing spaces and end punctuation from the path.
$redirect['path'] = preg_replace( "#($punctuation_pattern)+$#", '', $redirect['path'] );
if ( ! empty( $redirect['query'] ) ) {
// Remove trailing spaces and end punctuation from certain terminating query string args.
$redirect['query'] = preg_replace( "#((^|&)(p|page_id|cat|tag)=[^&]*?)($punctuation_pattern)+$#", '$1', $redirect['query'] );
// Clean up empty query strings.
$redirect['query'] = trim( preg_replace( '#(^|&)(p|page_id|cat|tag)=?(&|$)#', '&', $redirect['query'] ), '&' );
// Redirect obsolete feeds.
$redirect['query'] = preg_replace( '#(^|&)feed=rss(&|$)#', '$1feed=rss2$2', $redirect['query'] );
// Remove redundant leading ampersands.
$redirect['query'] = preg_replace( '#^??&*?#', '', $redirect['query'] );
}
// Strip /index.php/ when we're not using PATHINFO permalinks.
if ( ! $wp_rewrite->using_index_permalinks() ) {
$redirect['path'] = str_replace( '/' . $wp_rewrite->index . '/', '/', $redirect['path'] );
}
// Trailing slashes.
if ( is_object( $wp_rewrite ) && $wp_rewrite->using_permalinks()
&& ! $is_attachment_redirect
&& ! is_404() && ( ! is_front_page() || is_front_page() && get_query_var( 'paged' ) > 1 )
) {
$user_ts_type = '';
if ( get_query_var( 'paged' ) > 0 ) {
$user_ts_type = 'paged';
} else {
foreach ( array( 'single', 'category', 'page', 'day', 'month', 'year', 'home' ) as $type ) {
$func = 'is_' . $type;
if ( call_user_func( $func ) ) {
$user_ts_type = $type;
break;
}
}
}
$redirect['path'] = user_trailingslashit( $redirect['path'], $user_ts_type );
} elseif ( is_front_page() ) {
$redirect['path'] = trailingslashit( $redirect['path'] );
}
// Remove trailing slash for robots.txt or sitemap requests.
if ( is_robots()
|| ! empty( get_query_var( 'sitemap' ) ) || ! empty( get_query_var( 'sitemap-stylesheet' ) )
) {
$redirect['path'] = untrailingslashit( $redirect['path'] );
}
// Strip multiple slashes out of the URL.
if ( str_contains( $redirect['path'], '//' ) ) {
$redirect['path'] = preg_replace( '|/+|', '/', $redirect['path'] );
}
// Always trailing slash the Front Page URL.
if ( trailingslashit( $redirect['path'] ) === trailingslashit( $user_home['path'] ) ) {
$redirect['path'] = trailingslashit( $redirect['path'] );
}
$original_host_low = strtolower( $original['host'] );
$redirect_host_low = strtolower( $redirect['host'] );
/*
* Ignore differences in host capitalization, as this can lead to infinite redirects.
* Only redirect no-www <=> yes-www.
*/
if ( $original_host_low === $redirect_host_low
|| ( 'www.' . $original_host_low !== $redirect_host_low
&& 'www.' . $redirect_host_low !== $original_host_low )
) {
$redirect['host'] = $original['host'];
}
$compare_original = array( $original['host'], $original['path'] );
if ( ! empty( $original['port'] ) ) {
$compare_original[] = $original['port'];
}
if ( ! empty( $original['query'] ) ) {
$compare_original[] = $original['query'];
}
$compare_redirect = array( $redirect['host'], $redirect['path'] );
if ( ! empty( $redirect['port'] ) ) {
$compare_redirect[] = $redirect['port'];
}
if ( ! empty( $redirect['query'] ) ) {
$compare_redirect[] = $redirect['query'];
}
if ( $compare_original !== $compare_redirect ) {
$redirect_url = $redirect['scheme'] . '://' . $redirect['host'];
if ( ! empty( $redirect['port'] ) ) {
$redirect_url .= ':' . $redirect['port'];
}
$redirect_url .= $redirect['path'];
if ( ! empty( $redirect['query'] ) ) {
$redirect_url .= '?' . $redirect['query'];
}
}
if ( ! $redirect_url || $redirect_url === $requested_url ) {
return;
}
// Hex-encoded octets are case-insensitive.
if ( str_contains( $requested_url, '%' ) ) {
if ( ! function_exists( 'lowercase_octets' ) ) {
/**
* Converts the first hex-encoded octet match to lowercase.
*
* @since 3.1.0
* @ignore
*
* @param array $matches Hex-encoded octet matches for the requested URL.
* @return string Lowercased version of the first match.
*/
function lowercase_octets( $matches ) {
return strtolower( $matches[0] );
}
}
$requested_url = preg_replace_callback( '|%[a-fA-F0-9][a-fA-F0-9]|', 'lowercase_octets', $requested_url );
}
if ( $redirect_obj instanceof WP_Post ) {
$post_status_obj = get_post_status_object( get_post_status( $redirect_obj ) );
/*
* Unset the redirect object and URL if they are not readable by the user.
* This condition is a little confusing as the condition needs to pass if
* the post is not readable by the user. That's why there are ! (not) conditions
* throughout.
*/
if (
// Private post statuses only redirect if the user can read them.
! (
$post_status_obj->private &&
current_user_can( 'read_post', $redirect_obj->ID )
) &&
// For other posts, only redirect if publicly viewable.
! is_post_publicly_viewable( $redirect_obj )
) {
$redirect_obj = false;
$redirect_url = false;
}
}
/**
* Filters the canonical redirect URL.
*
* Returning false to this filter will cancel the redirect.
*
* @since 2.3.0
*
* @param string $redirect_url The redirect URL.
* @param string $requested_url The requested URL.
*/
$redirect_url = apply_filters( 'redirect_canonical', $redirect_url, $requested_url );
// Yes, again -- in case the filter aborted the request.
if ( ! $redirect_url || strip_fragment_from_url( $redirect_url ) === strip_fragment_from_url( $requested_url ) ) {
return;
}
if ( $do_redirect ) {
// Protect against chained redirects.
if ( ! redirect_canonical( $redirect_url, false ) ) {
wp_redirect( $redirect_url, 301 );
exit;
} else {
// Debug.
// die("1: $redirect_url<br />2: " . redirect_canonical( $redirect_url, false ) );
return;
}
} else {
return $redirect_url;
}
}
Hooks
- apply_filters( ‘redirect_canonical’, string $redirect_url, string $requested_url )
-
Filters the canonical redirect URL.
- apply_filters( ‘wp_signup_location’, string $sign_up_url )
-
Filters the Multisite sign up URL.
Changelog
| Version | Description |
|---|---|
| 2.3.0 | Introduced. |
Skip to note 3 content
Mishra Vinay
/** * Creates 301 redirects canonical */ function wpdocs_redirect_can() { // Is single Post 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' );I got multiple emails about canonical issue. If I have 2 categories both category URL was indexed with proper one canonical tag and both pages able to access.
This has not been automatically done by WP. Many paid plugins are available but programmatically I have done above code and working.
Skip to note 4 content
Khoi Pro
Remove Redirect for public var like ‘year’ in Custom Taxonomy.
For example, a link: /?event_category=xxx?year=2017
If you don’t add this filter:
– It redirects to /2016/
If you use this redirect:
– It remains at page /?event_category=xxx
This code is helpful for creating a filter in Taxonomies.
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; }