add_rewrite_tag( string $tag, string $regex, string $query = '' )

Add a new rewrite tag (like %postname%).


Description Description

The $query parameter is optional. If it is omitted you must ensure that you call this on, or before, the ‘init’ hook. This is because $query defaults to "$tag=", and for this to work a new query var has to be added.


Parameters Parameters

$tag

(string) (Required) Name of the new rewrite tag.

$regex

(string) (Required) Regular expression to substitute the tag for in rewrite rules.

$query

(string) (Optional) String to append to the rewritten query. Must end in '='.

Default value: ''


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Source Source

File: wp-includes/rewrite.php

function add_rewrite_tag( $tag, $regex, $query = '' ) {
	// validate the tag's name
	if ( strlen( $tag ) < 3 || $tag[0] != '%' || $tag[ strlen($tag) - 1 ] != '%' )
		return;

	global $wp_rewrite, $wp;

	if ( empty( $query ) ) {
		$qv = trim( $tag, '%' );
		$wp->add_query_var( $qv );
		$query = $qv . '=';
	}

	$wp_rewrite->add_rewrite_tag( $tag, $regex, $query );
}

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Changelog Changelog

Changelog
Version Description
2.1.0 Introduced.


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User Contributed Notes User Contributed Notes

  1. Skip to note 1 content
    Contributed by bcworkz

    In the following examples, imagine a site has a custom taxonomy ‘location’ and all posts are assigned a location term like “Paris” or “Madrid”. We add a rewrite tag “%location%” to establish the location query var. We also add a rewrite rule so that an URL such as example.com/goto/madrid/budget-lodging/ is properly handled.

    add_action('init', 'add_my_rewrites');
    function add_my_rewrites() {
        add_rewrite_tag('%location%', '([^&]+)', 'location=');
        add_rewrite_rule('^goto/([^/]*)/([^/]*)/?','index.php?location=$matches[1]&name=$matches[2]','top');
    }

    Even though rewrite tags look just like permalink structure tags, if you try to use your rewrite tag in a permalink structure, the URLs generated by WordPress will look something like example.com/goto/%location%/budget-lodging/. The proper term does not replace the rewrite tag as you might expect. To make your tag behave like a structure tag, use the “post_link” filter to replace the tag with the proper term.

    // Assign value to %location% rewrite tag
    add_filter('post_link', 'my_filter_post_link', 10, 2 );
    function my_filter_post_link( $permalink, $post ) {
    
        // bail if %location% tag is not present in the url:
        if ( false === strpos( $permalink, '%location%'))
            return $permalink;
    
        $terms = wp_get_post_terms( $post->ID, 'location');
        // set location, if no location is found, provide a default value.
        if ( 0 < count( $terms ))
            $location = $terms[0]->slug;
        else
            $location = 'timbuktu';
        $location = urlencode( $location );
        $permalink = str_replace('%location%', $location , $permalink );
     
        return $permalink;
    }

    Anytime you change something related to the Rewrite API, don’t forget to flush the rewrite rules! This can be done without code by going to Permalink Settings and clicking Save Changes. You don’t actually need to make any changes on the settings screen.

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