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Description

Remove rewrite rules and then recreate rewrite rules.

This function is useful when used with custom post types as it allows for automatic flushing of the WordPress rewrite rules (usually needs to be done manually for new custom post types). However, this is an expensive operation so it should only be used when absolutely necessary. See Usage section for more details.

Usage

Important:

• Flushing the rewrite rules is an expensive operation, there are tutorials and examples that suggest executing it on the 'init' hook. This is bad practice. It should be executed either on the 'shutdown' hook, or on plugin/theme (de)activation.
• Flush rules once (it's better to store the state in option, instead of `activation` or `deactivation`, because on MultiSite they are useless), or when you know that the rewrite rules need to be changed. Don't do it on any hook that will triggered on a routine basis. More detail information in the comments on WP Engineer's post: Custom Post Type and Permalink
• Make sure custom post types and taxonomies are properly registered before flushing rewrite rules, especially during plugin activation.

<?php flush_rewrite_rules( $hard ); ?>

Parameters

$hard

(boolean) (optional) Whether to update .htaccess (hard flush) or just update rewrite_rules transient (soft flush).

Default: true (hard flush)

Examples

This is how you would flush rewrite rules when a plugin is activated or deactivated:

register_deactivation_hook( __FILE__, 'flush_rewrite_rules' );
register_activation_hook( __FILE__, 'myplugin_flush_rewrites' );
function myplugin_flush_rewrites() {
	// call your CPT registration function here (it should also be hooked into 'init')
	myplugin_custom_post_types_registration();
	flush_rewrite_rules();
}

This is how you would flush rules on theme activation:

/* Flush rewrite rules for custom post types. */
add_action( 'after_switch_theme', 'flush_rewrite_rules' );

If you're developing a theme, while building it you can use this snippet of code that will flush rewrite rules when the file containing it is changed, or every 48 hours:

// do not use on live/production servers
add_action( 'init','maybe_rewrite_rules' );
function maybe_rewrite_rules() {

	$ver = filemtime( __FILE__ ); // Get the file time for this file as the version number
	$defaults = array( 'version' => 0, 'time' => time() );
	$r = wp_parse_args( get_option( __CLASS__ . '_flush', array() ), $defaults );

	if ( $r['version'] != $ver || $r['time'] + 172800 < time() ) { // Flush if ver changes or if 48hrs has passed.
		flush_rewrite_rules();
		// trace( 'flushed' );
		$args = array( 'version' => $ver, 'time' => time() );
		if ( ! update_option( __CLASS__ . '_flush', $args ) )
			add_option( __CLASS__ . '_flush', $args );
	}

}

Change Log

Since: 3.0

Source File

flush_rewrite_rules() is located in wp-includes/rewrite.php

Related

Articles

• Lesson: Rewrite API Overview
• Class: WP_Rewrite() - An overview of WordPress's built-in URL rewrite class.

Hooks

• Filter: root_rewrite_rules - Filters the rewrite rules generated for the root of your weblog.
• Filter: post_rewrite_rules - Filters the rewrite rules generated for permalink URLs.
• Filter: page_rewrite_rules - Filters the rewrite rules generated for your Pages.
• Filter: date_rewrite_rules - Filters the rewrite rules generated for dated archive URLs.
• Filter: search_rewrite_rules - Filters the rewrite rules generated for search URLs.
• Filter: comments_rewrite_rules - Filters the rewrite rules generated for the latest comment feed URLs.
• Filter: author_rewrite_rules - Filters the rewrite rules generated for author archive URLs.
• Filter: rewrite_rules_array - Filters all the rewrite rules at once.
• Filter: {$permastruct}_rewrite_rules - Can be used to create or modify rewrite rules for any custom permastructs, such as taxonomies or custom post types.
• Action: generate_rewrite_rules - Runs after all the rules have been created.

Functions

• add_rewrite_tag() - Can be used to allow WordPress to recognize custom variables (particularly custom querystring variables).
• add_rewrite_rule() - Allows you to specify new, custom rewrite rules.
• add_rewrite_endpoint() - Add a new endpoint like /trackback/
• flush_rules() - Regenerate the rewrite rules and save them to the database.
• flush_rewrite_rules() - Remove rewrite rules and then recreate rewrite rules.
• generate_rewrite_rules() - Generates rewrite rules from a permalink structure
• add_permastruct() - Add a new permastruct
• add_feed()- Add a new feed type like /atom1/