redirect_guess_404_permalink()

Attempts to guess the correct URL based on query vars

Return

(false|string) The correct URL if one is found. False on failure.

Source

File: wp-includes/canonical.php 

function redirect_guess_404_permalink() {
	global $wpdb;

	if ( get_query_var('name') ) {
		$where = $wpdb->prepare("post_name LIKE %s", $wpdb->esc_like( get_query_var('name') ) . '%');

		// if any of post_type, year, monthnum, or day are set, use them to refine the query
		if ( get_query_var('post_type') )
			$where .= $wpdb->prepare(" AND post_type = %s", get_query_var('post_type'));
		else
			$where .= " AND post_type IN ('" . implode( "', '", get_post_types( array( 'public' => true ) ) ) . "')";

		if ( get_query_var('year') )
			$where .= $wpdb->prepare(" AND YEAR(post_date) = %d", get_query_var('year'));
		if ( get_query_var('monthnum') )
			$where .= $wpdb->prepare(" AND MONTH(post_date) = %d", get_query_var('monthnum'));
		if ( get_query_var('day') )
			$where .= $wpdb->prepare(" AND DAYOFMONTH(post_date) = %d", get_query_var('day'));

		$post_id = $wpdb->get_var("SELECT ID FROM $wpdb->posts WHERE $where AND post_status = 'publish'");
		if ( ! $post_id )
			return false;
		if ( get_query_var( 'feed' ) )
			return get_post_comments_feed_link( $post_id, get_query_var( 'feed' ) );
		elseif ( get_query_var( 'page' ) && 1 < get_query_var( 'page' ) )
			return trailingslashit( get_permalink( $post_id ) ) . user_trailingslashit( get_query_var( 'page' ), 'single_paged' );
		else
			return get_permalink( $post_id );
	}

	return false;
}

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Related

Uses

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

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

Retrieves the permalink for the post comments feed.
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/wp-db.php: wpdb::prepare()

Prepares a SQL query for safe execution. Uses sprintf()-like syntax.
wp-includes/wp-db.php: wpdb::esc_like()

First half of escaping for LIKE special characters % and _ before preparing for MySQL.
wp-includes/wp-db.php: wpdb::get_var()

Retrieve one variable from the database.
wp-includes/post.php: get_post_types()

Get a list of all registered post type objects.
wp-includes/formatting.php: trailingslashit()

Appends a trailing slash.
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Used By

Used By
Used By Description
wp-includes/canonical.php: redirect_canonical()

Redirects incoming links to the proper URL based on the site url.

Changelog

Changelog
Version Description
WP-2.3.0 Introduced.