pre_wp_nav_menu │ filter-hook │ WP 3.9.0

Allows you to change the output of wp_nav_menu() at an early stage, before the function's main code runs.

Before the menu is generated, the filter can stop wp_nav_menu() from running or supply already generated HTML that is immediately displayed or returned, depending on the $args->echo parameter.

Usage

add_filter( 'pre_wp_nav_menu', 'wp_kama_pre_wp_nav_menu_filter', 10, 2 );

/**
 * Function for `pre_wp_nav_menu` filter-hook.
 * 
 * @param string|null $output Nav menu output to short-circuit with.
 * @param stdClass    $args   An object containing wp_nav_menu() arguments.
 *
 * @return string|null
 */
function wp_kama_pre_wp_nav_menu_filter( $output, $args ){
	// filter...
	return $output;
}

$output(string/null)

Value that determines how wp_nav_menu() proceeds.

• If null, execution continues.
• If the value is not null, the rest of the code is skipped and the supplied value is returned. If echo = true was specified, the result is displayed.

Default: null

$args(stdClass)

Object containing the arguments passed to wp_nav_menu(), merged with the defaults.

Examples

#1 Display an additional menu for logged-in users

This example assumes there are two menu locations: header-menu and header-menu-user-logged. Logged-out users see the menu assigned to header-menu; logged-in users additionally see the menu assigned to menu-user-logged.

// In header.php
wp_nav_menu( [
	'theme_location' => 'header-menu',
] );

// In functions.php
add_action( 'after_setup_theme', 'dev_menu_setup' );

function dev_menu_setup() {
	register_nav_menus( [
		'header-menu'      => 'Top menu',
		'menu-user-logged' => 'Top menu for logged-in users',
	] );
}

add_filter( 'pre_wp_nav_menu', 'change_pre_wp_nav_menu', 10, 2 );

function change_pre_wp_nav_menu( $output, $args ) {
	if ( $args->theme_location === 'header-menu' && is_user_logged_in() ) {
		wp_nav_menu( [
			'theme_location' => 'menu-user-logged',
		] );
	}

	return $output;
}