Cached navigation menu

Cached navigation menu

Introduced in WordPress 3.0, the new menu system is definitely an improvement to WordPress. But using transients, we can even do something better, a menu with the same functionality but without the huge database requests.

< ?php /** * Wrapper function around wp_nav_menu() that will cache the wp_nav_menu for all tag/category * pages used in the nav menus * @see http://lookup.hitchhackerguide.com/wp_nav_menu for $args * @author tott */ function hh_cached_nav_menu( $args = array(), $prime_cache = false ) { global $wp_query; $queried_object_id = empty( $wp_query->queried_object_id ) ? 0 : (int) $wp_query->queried_object_id;

// If design of navigation menus differs per queried object use the key below

// $nav_menu_key = md5( serialize( $args ) . ‘-‘ . $queried_object_id );

// Otherwise

$nav_menu_key = md5( serialize( $args ) );

$my_args = wp_parse_args( $args );

$my_args = apply_filters( ‘wp_nav_menu_args’, $my_args );

$my_args = (object) $my_args;

if ( ( isset( $my_args->echo ) && true === $my_args->echo )

!isset( $my_args->echo ) ) {

$echo = true;

} else {

$echo = false;

}

$skip_cache = false;

$use_cache = ( true === $prime_cache ) ? false : true;

// If design of navigation menus differs per queried object comment out this section

//*

if ( is_singular() ) {

$skip_cache = true;

} else if ( !in_array( $queried_object_id, hh_get_nav_menu_cache_objects( $use_cache ) ) ) {

$skip_cache = true;

}

//*/

if ( true === $skip_cache

true === $prime_cache

false === ( $nav_menu = get_transient( $nav_menu_key ) ) ) {

if ( false === $echo ) {

$nav_menu = wp_nav_menu( $args );

} else {

ob_start();

wp_nav_menu( $args );

$nav_menu = ob_get_clean();

}

if ( false === $skip_cache )

set_transient( $nav_menu_key, $nav_menu );

}

if ( true === $echo )

echo $nav_menu;

else

return $nav_menu;

}

/**

• Invalidate navigation menu when an update occurs

*/

function hh_update_nav_menu_objects( $menu_id = null, $menu_data = null ) {

hh_cached_nav_menu( array( ‘echo’ => false ), $prime_cache = true );

}

add_action( ‘wp_update_nav_menu’, ‘hh_update_nav_menu_objects’ );

/**

• Helper function that returns the object_ids we’d like to cache

*/

function hh_get_nav_menu_cache_objects( $use_cache = true ) {

$object_ids = get_transient( ‘hh_nav_menu_cache_object_ids’ );

if ( true === $use_cache && !empty( $object_ids ) ) {

return $object_ids;

}

$object_ids = $objects = array();

$menus = wp_get_nav_menus();

foreach ( $menus as $menu_maybe ) {

if ( $menu_items = wp_get_nav_menu_items( $menu_maybe->term_id ) ) {

foreach( $menu_items as $menu_item ) {

if ( preg_match( “#.*/category/([^/]+)/?$#”, $menu_item->url, $match ) )

$objects[‘category’][] = $match[1];

if ( preg_match( “#.*/tag/([^/]+)/?$#”, $menu_item->url, $match ) )

$objects[‘post_tag’][] = $match[1];

}

}

}

if ( !empty( $objects ) ) {

foreach( $objects as $taxonomy => $term_names ) {

foreach( $term_names as $term_name ) {

$term = get_term_by( ‘slug’, $term_name, $taxonomy );

if ( $term )

$object_ids[] = $term->term_id;

}

}

}

$object_ids[] = 0; // that’s for the homepage

set_transient( ‘hh_nav_menu_cache_object_ids’, $object_ids );

return $object_ids;

}