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wp_old_slug_redirect()

Redirect old slugs to the correct permalink.

Description

Attempts to find the current slug from the past slugs.

Source

File: wp-includes/query.php 

function wp_old_slug_redirect() {
	if ( is_404() && '' !== get_query_var( 'name' ) ) {
		// Guess the current post type based on the query vars.
		if ( get_query_var( 'post_type' ) ) {
			$post_type = get_query_var( 'post_type' );
		} elseif ( get_query_var( 'attachment' ) ) {
			$post_type = 'attachment';
		} elseif ( get_query_var( 'pagename' ) ) {
			$post_type = 'page';
		} else {
			$post_type = 'post';
		}

		if ( is_array( $post_type ) ) {
			if ( count( $post_type ) > 1 ) {
				return;
			}
			$post_type = reset( $post_type );
		}

		// Do not attempt redirect for hierarchical post types.
		if ( is_post_type_hierarchical( $post_type ) ) {
			return;
		}

		$id = _find_post_by_old_slug( $post_type );

		if ( ! $id ) {
			$id = _find_post_by_old_date( $post_type );
		}

		/**
		 * Filters the old slug redirect post ID.
		 *
		 * @since 4.9.3
		 *
		 * @param int $id The redirect post ID.
		 */
		$id = apply_filters( 'old_slug_redirect_post_id', $id );

		if ( ! $id ) {
			return;
		}

		$link = get_permalink( $id );

		if ( get_query_var( 'paged' ) > 1 ) {
			$link = user_trailingslashit( trailingslashit( $link ) . 'page/' . get_query_var( 'paged' ) );
		} elseif ( is_embed() ) {
			$link = user_trailingslashit( trailingslashit( $link ) . 'embed' );
		}

		/**
		 * Filters the old slug redirect URL.
		 *
		 * @since 4.4.0
		 *
		 * @param string $link The redirect URL.
		 */
		$link = apply_filters( 'old_slug_redirect_url', $link );

		if ( ! $link ) {
			return;
		}

		wp_redirect( $link, 301 ); // Permanent redirect.
		exit;
	}
}

Uses

Uses Description
wp-includes/query.php: _find_post_by_old_slug()

Find the post ID for redirecting an old slug.
wp-includes/query.php: _find_post_by_old_date()

Find the post ID for redirecting an old date.
wp-includes/query.php: old_slug_redirect_post_id

Filters the old slug redirect post ID.
wp-includes/query.php: old_slug_redirect_url

Filters the old slug redirect URL.
wp-includes/query.php: is_embed()

Is the query for an embedded post?
wp-includes/formatting.php: trailingslashit()

Appends a trailing slash.
wp-includes/pluggable.php: wp_redirect()

Redirects to another page.
wp-includes/query.php: is_404()

Determines whether the query has resulted in a 404 (returns no results).
wp-includes/query.php: get_query_var()

Retrieve variable in the WP_Query class.
wp-includes/link-template.php: get_permalink()

Retrieves the full permalink for the current post or post ID.
wp-includes/link-template.php: user_trailingslashit()

Retrieves a trailing-slashed string if the site is set for adding trailing slashes.
wp-includes/plugin.php: apply_filters()

Calls the callback functions that have been added to a filter hook.
wp-includes/post.php: is_post_type_hierarchical()

Whether the post type is hierarchical.

Changelog

Version Description
2.1.0 Introduced.

© 2003–2019 WordPress Foundation
Licensed under the GNU GPLv2+ License.
https://developer.wordpress.org/reference/functions/wp_old_slug_redirect