add_rewrite_tag() WordPress Function
The add_rewrite_tag() function allows you to specify a new rewrite tag and its regular expression. This function should be used when you need to specify a new rewrite tag that does not already have a built-in function.
add_rewrite_tag( string $tag, string $regex, string $query = '' ) #
Adds a new rewrite tag (like %postname%).
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
- $tag
(string)(Required)Name of the new rewrite tag.
- $regex
(string)(Required)Regular expression to substitute the tag for in rewrite rules.
- $query
(string)(Optional) String to append to the rewritten query. Must end in '='.
Default value: ''
More Information
This function can be used to make WordPress aware of custom querystring variables. Generally, it’s used in combination with add_rewrite_rule() to create rewrite rules for pages with custom templates.
If you use this function to declare a rewrite tag that already exists, the existing tag will be overwritten.
This function must be called on init or earlier.
What it does
- Gets a query var name by stripping the % signs from the name of the tag: trim($tag, ‘%’)
- Calls $wp_rewrite->add_rewrite_tag() with the name, generated QV name and regex.
- Adds the QV as a query var (again, this could be done by filtering query_vars but it might be nicer to add a function to the WP class that stores ‘extra’ QVs like above)
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
| Version | Description |
|---|---|
| 2.1.0 | Introduced. |