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Function Reference/flush rewrite rules

Contents

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).

Important: Rewrite rules must be flushed on activation or deactivation to avoid unnecessary rewrite rule flushing.

More detailed information is available on WP Engineer (more information in the comments) ... http://wpengineer.com/2044/custom-post-type-and-permalink/

Usage

<?php flush_rewrite_rules$hard ); ?>

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. Instead you should flush rewrite rules on the activation hook of a plugin, or when you know that the rewrite rules need to be changed ( e.g. the addition of a new taxonomy or post type in your code ).

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:

function myplugin_activate() {
	// register taxonomies/post types here
	flush_rewrite_rules();
}

register_activation_hook( __FILE__, 'myplugin_activate' );

function myplugin_deactivate() {
	flush_rewrite_rules();
}
register_deactivation_hook( __FILE__, 'myplugin_deactivate' );

This is how you would flush rules on theme activation:

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

/* Flush your rewrite rules */
function bt_flush_rewrite_rules() {
     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

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