Question

wp_nav_menu( array $args = array() )

Displays a navigation menu.

---

description

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参数

$args

(array) (Optional) Array of nav menu arguments.

• 'menu'
  (int|string|WP_Term) Desired menu. Accepts (matching in order) id, slug, name, menu object.
• 'menu_class'
  (string) CSS class to use for the ul element which forms the menu. Default 'menu'.
• 'menu_id'
  (string) The ID that is applied to the ul element which forms the menu. Default is the menu slug, incremented.
• 'container'
  (string) Whether to wrap the ul, and what to wrap it with. Default 'div'.
• 'container_class'
  (string) Class that is applied to the container. Default 'menu-{menu slug}-container'.
• 'container_id'
  (string) The ID that is applied to the container.
• 'fallback_cb'
  (callable|bool) If the menu doesn't exists, a callback function will fire. Default is 'wp_page_menu'. Set to false for no fallback.
• 'before'
  (string) Text before the link markup.
• 'after'
  (string) Text after the link markup.
• 'link_before'
  (string) Text before the link text.
• 'link_after'
  (string) Text after the link text.
• 'echo'
  (bool) Whether to echo the menu or return it. Default true.
• 'depth'
  (int) How many levels of the hierarchy are to be included. 0 means all. Default 0.
• 'walker'
  (object) Instance of a custom walker class.
• 'theme_location'
  (string) Theme location to be used. Must be registered with register_nav_menu() in order to be selectable by the user.
• 'items_wrap'
  (string) How the list items should be wrapped. Default is a ul with an id and class. Uses printf() format with numbered placeholders.
• 'item_spacing'
  (string) Whether to preserve whitespace within the menu's HTML. Accepts 'preserve' or 'discard'. Default 'preserve'.

Default value: array()

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返回值

(string|false|void) Menu output if $echo is false, false if there are no items or no menu was found.

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源代码

File: wp-includes/nav-menu-template.php

function wp_nav_menu( $args = array() ) {
	static $menu_id_slugs = array();

	$defaults = array( 'menu' => '', 'container' => 'div', 'container_class' => '', 'container_id' => '', 'menu_class' => 'menu', 'menu_id' => '',
	'echo' => true, 'fallback_cb' => 'wp_page_menu', 'before' => '', 'after' => '', 'link_before' => '', 'link_after' => '', 'items_wrap' => '<ul id="%1$s" class="%2$s">%3$s</ul>', 'item_spacing' => 'preserve',
	'depth' => 0, 'walker' => '', 'theme_location' => '' );

	$args = wp_parse_args( $args, $defaults );

	if ( ! in_array( $args['item_spacing'], array( 'preserve', 'discard' ), true ) ) {
		// invalid value, fall back to default.
		$args['item_spacing'] = $defaults['item_spacing'];
	}

	/**
	 * Filters the arguments used to display a navigation menu.
	 *
	 * @since 3.0.0
	 *
	 * @see wp_nav_menu()
	 *
	 * @param array $args Array of wp_nav_menu() arguments.
	 */
	$args = apply_filters( 'wp_nav_menu_args', $args );
	$args = (object) $args;

	/**
	 * Filters whether to short-circuit the wp_nav_menu() output.
	 *
	 * Returning a non-null value to the filter will short-circuit
	 * wp_nav_menu(), echoing that value if $args->echo is true,
	 * returning that value otherwise.
	 *
	 * @since 3.9.0
	 *
	 * @see wp_nav_menu()
	 *
	 * @param string|null $output Nav menu output to short-circuit with. Default null.
	 * @param stdClass    $args   An object containing wp_nav_menu() arguments.
	 */
	$nav_menu = apply_filters( 'pre_wp_nav_menu', null, $args );

	if ( null !== $nav_menu ) {
		if ( $args->echo ) {
			echo $nav_menu;
			return;
		}

		return $nav_menu;
	}

	// Get the nav menu based on the requested menu
	$menu = wp_get_nav_menu_object( $args->menu );

	// Get the nav menu based on the theme_location
	if ( ! $menu && $args->theme_location && ( $locations = get_nav_menu_locations() ) && isset( $locations[ $args->theme_location ] ) )
		$menu = wp_get_nav_menu_object( $locations[ $args->theme_location ] );

	// get the first menu that has items if we still can't find a menu
	if ( ! $menu && !$args->theme_location ) {
		$menus = wp_get_nav_menus();
		foreach ( $menus as $menu_maybe ) {
			if ( $menu_items = wp_get_nav_menu_items( $menu_maybe->term_id, array( 'update_post_term_cache' => false ) ) ) {
				$menu = $menu_maybe;
				break;
			}
		}
	}

	if ( empty( $args->menu ) ) {
		$args->menu = $menu;
	}

	// If the menu exists, get its items.
	if ( $menu && ! is_wp_error($menu) && !isset($menu_items) )
		$menu_items = wp_get_nav_menu_items( $menu->term_id, array( 'update_post_term_cache' => false ) );

	/*
	 * If no menu was found:
	 *  - Fall back (if one was specified), or bail.
	 *
	 * If no menu items were found:
	 *  - Fall back, but only if no theme location was specified.
	 *  - Otherwise, bail.
	 */
	if ( ( !$menu || is_wp_error($menu) || ( isset($menu_items) && empty($menu_items) && !$args->theme_location ) )
		&& isset( $args->fallback_cb ) && $args->fallback_cb && is_callable( $args->fallback_cb ) )
			return call_user_func( $args->fallback_cb, (array) $args );

	if ( ! $menu || is_wp_error( $menu ) )
		return false;

	$nav_menu = $items = '';

	$show_container = false;
	if ( $args->container ) {
		/**
		 * Filters the list of HTML tags that are valid for use as menu containers.
		 *
		 * @since 3.0.0
		 *
		 * @param array $tags The acceptable HTML tags for use as menu containers.
		 *                    Default is array containing 'div' and 'nav'.
		 */
		$allowed_tags = apply_filters( 'wp_nav_menu_container_allowedtags', array( 'div', 'nav' ) );
		if ( is_string( $args->container ) && in_array( $args->container, $allowed_tags ) ) {
			$show_container = true;
			$class = $args->container_class ? ' class="' . esc_attr( $args->container_class ) . '"' : ' class="menu-'. $menu->slug .'-container"';
			$id = $args->container_id ? ' id="' . esc_attr( $args->container_id ) . '"' : '';
			$nav_menu .= '<'. $args->container . $id . $class . '>';
		}
	}

	// Set up the $menu_item variables
	_wp_menu_item_classes_by_context( $menu_items );

	$sorted_menu_items = $menu_items_with_children = array();
	foreach ( (array) $menu_items as $menu_item ) {
		$sorted_menu_items[ $menu_item->menu_order ] = $menu_item;
		if ( $menu_item->menu_item_parent )
			$menu_items_with_children[ $menu_item->menu_item_parent ] = true;
	}

	// Add the menu-item-has-children class where applicable
	if ( $menu_items_with_children ) {
		foreach ( $sorted_menu_items as &$menu_item ) {
			if ( isset( $menu_items_with_children[ $menu_item->ID ] ) )
				$menu_item->classes[] = 'menu-item-has-children';
		}
	}

	unset( $menu_items, $menu_item );

	/**
	 * Filters the sorted list of menu item objects before generating the menu's HTML.
	 *
	 * @since 3.1.0
	 *
	 * @param array    $sorted_menu_items The menu items, sorted by each menu item's menu order.
	 * @param stdClass $args              An object containing wp_nav_menu() arguments.
	 */
	$sorted_menu_items = apply_filters( 'wp_nav_menu_objects', $sorted_menu_items, $args );

	$items .= walk_nav_menu_tree( $sorted_menu_items, $args->depth, $args );
	unset($sorted_menu_items);

	// Attributes
	if ( ! empty( $args->menu_id ) ) {
		$wrap_id = $args->menu_id;
	} else {
		$wrap_id = 'menu-' . $menu->slug;
		while ( in_array( $wrap_id, $menu_id_slugs ) ) {
			if ( preg_match( '#-(\d+)$#', $wrap_id, $matches ) )
				$wrap_id = preg_replace('#-(\d+)$#', '-' . ++$matches[1], $wrap_id );
			else
				$wrap_id = $wrap_id . '-1';
		}
	}
	$menu_id_slugs[] = $wrap_id;

	$wrap_class = $args->menu_class ? $args->menu_class : '';

	/**
	 * Filters the HTML list content for navigation menus.
	 *
	 * @since 3.0.0
	 *
	 * @see wp_nav_menu()
	 *
	 * @param string   $items The HTML list content for the menu items.
	 * @param stdClass $args  An object containing wp_nav_menu() arguments.
	 */
	$items = apply_filters( 'wp_nav_menu_items', $items, $args );
	/**
	 * Filters the HTML list content for a specific navigation menu.
	 *
	 * @since 3.0.0
	 *
	 * @see wp_nav_menu()
	 *
	 * @param string   $items The HTML list content for the menu items.
	 * @param stdClass $args  An object containing wp_nav_menu() arguments.
	 */
	$items = apply_filters( "wp_nav_menu_{$menu->slug}_items", $items, $args );

	// Don't print any markup if there are no items at this point.
	if ( empty( $items ) )
		return false;

	$nav_menu .= sprintf( $args->items_wrap, esc_attr( $wrap_id ), esc_attr( $wrap_class ), $items );
	unset( $items );

	if ( $show_container )
		$nav_menu .= '</' . $args->container . '>';

	/**
	 * Filters the HTML content for navigation menus.
	 *
	 * @since 3.0.0
	 *
	 * @see wp_nav_menu()
	 *
	 * @param string   $nav_menu The HTML content for the navigation menu.
	 * @param stdClass $args     An object containing wp_nav_menu() arguments.
	 */
	$nav_menu = apply_filters( 'wp_nav_menu', $nav_menu, $args );

	if ( $args->echo )
		echo $nav_menu;
	else
		return $nav_menu;
}

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更新日志

Version	description
4.7.0	Added the item_spacing argument.
3.0.0	Introduced.

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More Information

Usage

wp_nav_menu( $args );

Given a theme_location parameter, the function displays the menu assigned to that location. If no such location exists or no menu is assigned to it, the parameter fallback_cb will determine what is displayed.

If not given a theme_location parameter, the function displays

• the menu matching the ID, slug, or name given by the menu parameter;
• otherwise, the first non-empty menu;
• otherwise (or if the menu given by menu is empty), output of the function given by the fallback_cb parameter (wp_page_menu(), by default);
• otherwise nothing.

Menu Item CSS Classes

The following classes are applied to menu items, i.e. to the HTML <li> tags, generated by wp_nav_menu():

All Menu Items

• .menu-item
  This class is added to every menu item.
• .menu-item-has-children
  This class is added to menu item which has sub-items .
• .menu-item-object-{object}
  This class is added to every menu item, where {object} is either a post type or a taxonomy.
• .menu-item-object-category
  This class is added to menu items that correspond to a category.
• .menu-item-object-tag
  This class is added to menu items that correspond to a tag.
• .menu-item-object-page
  This class is added to menu items that correspond to static pages.
• .menu-item-object-{custom}
  This class is added to menu items that correspond to a custom post type or a custom taxonomy.
• .menu-item-type-{type}
  This class is added to every menu item, where {type} is either “post_type” or “taxonomy”.
• .menu-item-type-post_type
  This class is added to menu items that correspond to post types: i.e. static pages or custom post types.
• .menu-item-type-taxonomy
  This class is added to menu items that correspond to taxonomies: i.e. categories, tags, or custom taxonomies.

Current-Page Menu Items

• .current-menu-item
  This class is added to menu items that correspond to the currently rendered page.

Current-Page Parent Menu Items

• .current-menu-parent
  This class is added to menu items that correspond to the hierarchical parent of the currently rendered page.
• .current-{object}-parent
  This class is added to menu items that correspond to the hierachical parent of the currently rendered object, where {object} corresponds to the the value used for .menu-item-object-{object}.
• .current-{type}-parent
  This class is added to menu items that correspond to the hierachical parent of the currently rendered type, where {type} corresponds to the the value used for .menu-item-type-{type}.

Current-Page Ancestor Menu Items

• .current-menu-ancestor
  This class is added to menu items that correspond to a hierarchical ancestor of the currently rendered page.
• .current-{object}-ancestor
  This class is added to menu items that correspond to a hierachical ancestor of the currently rendered object, where {object} corresponds to the the value used for .menu-item-object-{object}.
• .current-{type}-ancestor
  This class is added to menu items that correspond to a hierachical ancestor of the currently rendered type, where {type} corresponds to the the value used for .menu-item-type-{type}.

Site Front Page Menu Items

• .menu-item-home
  This class is added to menu items that correspond to the site front page.

Backward Compatibility with wp_page_menu()

The following classes are added to maintain backward compatibility with the [[Function Reference/wp_page_menu|wp_page_menu()]] function output:

• .page_item
  This class is added to menu items that correspond to a static page.
• .page_item_has_children
  This class is added to menu items that have sub pages to it.
• .page-item-$ID
  This class is added to menu items that correspond to a static page, where $ID is the static page ID.
• .current_page_item
  This class is added to menu items that correspond to the currently rendered static page.
• .current_page_parent
  This class is added to menu items that correspond to the hierarchical parent of the currently rendered static page.
• .current_page_ancestor
  This class is added to menu items that correspond to a hierarchical ancestor of the currently rendered static page.

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相关函数

Uses

• wp-includes/formatting.php: esc_attr()
• wp-includes/functions.php: wp_parse_args()
• wp-includes/plugin.php: apply_filters()
• wp-includes/nav-menu-template.php: _wp_menu_item_classes_by_context()
• wp-includes/nav-menu-template.php: walk_nav_menu_tree()
• wp-includes/nav-menu-template.php: wp_nav_menu_args
• wp-includes/nav-menu-template.php: pre_wp_nav_menu
• wp-includes/nav-menu-template.php: wp_nav_menu_container_allowedtags
• wp-includes/nav-menu-template.php: wp_nav_menu_objects
• wp-includes/nav-menu-template.php: wp_nav_menu_items
• wp-includes/nav-menu-template.php: wp_nav_menu_{$menu->slug}_items
• wp-includes/nav-menu-template.php: wp_nav_menu
• wp-includes/nav-menu.php: wp_get_nav_menus()
• wp-includes/nav-menu.php: wp_get_nav_menu_items()
• wp-includes/nav-menu.php: wp_get_nav_menu_object()
• wp-includes/nav-menu.php: get_nav_menu_locations()
• wp-includes/load.php: is_wp_error()
Show 12 more uses Hide more uses

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Used By

• wp-includes/class-wp-customize-nav-menus.php: WP_Customize_Nav_Menus::render_nav_menu_partial()
• wp-includes/widgets/class-wp-nav-menu-widget.php: WP_Nav_Menu_Widget::widget()

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User Contributed Notes

1. Skip to note content You must log in to vote on the helpfulness of this noteVote results for this note: 9You must log in to vote on the helpfulness of this note Contributed by Drew Jaynes

   Removing the ul wrap

   This example will remove the unordered list wrap around the list items. Replacing the wrap HTML with the %3$s specifier results in only outputting the HTML list content for the menu items, because items_wrap is built using sprintf()

   items_wrap default before:

   
   <ul id="%1$s" class="%2$s">%3$s</ul>
   

   items_wrap after:

   
   %3$s
   

   Example:

   
   wp_nav_menu( array( 'items_wrap' => '%3$s' ) );
   

Using a Custom Walker Function

For deeper conditional classes, you’ll need to use a custom walker function (created in the 'walker' => new Your_Walker_Function argument).

The simplest way to build a new walker function is to copy and extend the default class (Walker_Nav_Menu) from /wp-includes/nav-menu-template.php and simply customize what you need.

Example:

This custom walker function will add several conditional classes to your nav menu (i.e. sub-menu, even/odd, etc):

wp_nav_menu( array(
	'menu'   => 'Something custom walker',
	'walker' => new WPDocs_Walker_Nav_Menu()
) );

/**
 * Custom walker class.
 */
class WPDocs_Walker_Nav_Menu extends Walker_Nav_Menu {

	/**
	 * Starts the list before the elements are added.
	 *
	 * Adds classes to the unordered list sub-menus.
	 *
	 * @param string $output Passed by reference. Used to append additional content.
	 * @param int    $depth  Depth of menu item. Used for padding.
	 * @param array  $args   An array of arguments. @see wp_nav_menu()
	 */
	function start_lvl( &$output, $depth = 0, $args = array() ) {
		// Depth-dependent classes.
		$indent = ( $depth > 0  ? str_repeat( "\t", $depth ) : '' ); // code indent
		$display_depth = ( $depth + 1); // because it counts the first submenu as 0
		$classes = array(
			'sub-menu',
			( $display_depth % 2  ? 'menu-odd' : 'menu-even' ),
			( $display_depth >=2 ? 'sub-sub-menu' : '' ),
			'menu-depth-' . $display_depth
		);
		$class_names = implode( ' ', $classes );

		// Build HTML for output.
		$output .= "\n" . $indent . '<ul class="' . $class_names . '">' . "\n";
	}

	/**
	 * Start the element output.
	 *
	 * Adds main/sub-classes to the list items and links.
	 *
	 * @param string $output Passed by reference. Used to append additional content.
	 * @param object $item   Menu item data object.
	 * @param int    $depth  Depth of menu item. Used for padding.
	 * @param array  $args   An array of arguments. @see wp_nav_menu()
	 * @param int    $id     Current item ID.
	 */
	function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
		global $wp_query;
		$indent = ( $depth > 0 ? str_repeat( "\t", $depth ) : '' ); // code indent

		// Depth-dependent classes.
		$depth_classes = array(
			( $depth == 0 ? 'main-menu-item' : 'sub-menu-item' ),
			( $depth >=2 ? 'sub-sub-menu-item' : '' ),
			( $depth % 2 ? 'menu-item-odd' : 'menu-item-even' ),
			'menu-item-depth-' . $depth
		);
		$depth_class_names = esc_attr( implode( ' ', $depth_classes ) );

		// Passed classes.
		$classes = empty( $item->classes ) ? array() : (array) $item->classes;
		$class_names = esc_attr( implode( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item ) ) );

		// Build HTML.
		$output .= $indent . '<li id="nav-menu-item-'. $item->ID . '" class="' . $depth_class_names . ' ' . $class_names . '">';

		// Link attributes.
		$attributes  = ! empty( $item->attr_title ) ? ' title="'  . esc_attr( $item->attr_title ) .'"' : '';
		$attributes .= ! empty( $item->target )     ? ' target="' . esc_attr( $item->target     ) .'"' : '';
		$attributes .= ! empty( $item->xfn )        ? ' rel="'    . esc_attr( $item->xfn        ) .'"' : '';
		$attributes .= ! empty( $item->url )        ? ' href="'   . esc_attr( $item->url        ) .'"' : '';
		$attributes .= ' class="menu-link ' . ( $depth > 0 ? 'sub-menu-link' : 'main-menu-link' ) . '"';

		// Build HTML output and pass through the proper filter.
		$item_output = sprintf( '%1$s<a%2$s>%3$s%4$s%5$s</a>%6$s',
			$args->before,
			$attributes,
			$args->link_before,
			apply_filters( 'the_title', $item->title, $item->ID ),
			$args->link_after,
			$args->after
		);
		$output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
	}
}

Different menus for logged-in users

This example would cause a menu to show for logged-in users and a different menu for users not logged-in.

wp_nav_menu( array(
	'theme_location' => is_user_logged_in() ? 'logged-in-menu' : 'logged-out-menu'
) );

Default example

Shows the first non-empty menu or wp_page_menu().

<?php wp_nav_menu(); ?>

Adding Conditional Classes to Menu Items

This example would let you add a custom class to a menu item based on the condition you specify. Don’t forget to change the condition.

/**
 * Filter the CSS class for a nav menu based on a condition.
 *
 * @param array  $classes The CSS classes that are applied to the menu item's <li> element.
 * @param object $item    The current menu item.
 * @return array (maybe) modified nav menu class.
 */
function wpdocs_special_nav_class( $classes, $item ) {
	if ( is_single() && 'Blog' == $item->title ) {
		// Notice you can change the conditional from is_single() and $item->title
		$classes[] = "special-class";
	}
	return $classes;
}
add_filter( 'nav_menu_css_class' , 'wpdocs_special_nav_class' , 10, 2 );

Targeting a specific menu

wp_nav_menu( array(
	'menu' => 'Project Nav'
) );

Targeting a specific menu with no fallback to wp_page_menu()

In the case that no menu matching menu is found, it seems that passing a bogus theme_location is the only way to prevent falling back to the first non-empty menu:

wp_nav_menu( array(
	'menu'           => 'Project Nav', // Do not fall back to first non-empty menu.
	'theme_location' => '__no_such_location'
	'fallback_cb'    => false // Do not fall back to wp_page_menu()
) );

To clarify link_before vs before, and link_after vs after

The link_before / link_after values are output WITHIN the link.
Whereas, before / after values are output OUTSIDE of the link, but within the list item.

For example:
{before}{link_before}Link Text{link_after}{after}

How to add a parent class for menu item

Sometimes you may need to add a class to a menu item if it has sub-menus.

/**
 * Add a parent CSS class for nav menu items.
 *
 * @param array  $items The menu items, sorted by each menu item's menu order.
 * @return array (maybe) modified parent CSS class.
 */
function wpdocs_add_menu_parent_class( $items ) {
	$parents = array();

	// Collect menu items with parents.
	foreach ( $items as $item ) {
		if ( $item->menu_item_parent && $item->menu_item_parent > 0 ) {
			$parents[] = $item->menu_item_parent;
		}
	}

	// Add class.
	foreach ( $items as $item ) {
		if ( in_array( $item->ID, $parents ) ) {
			$item->classes[] = 'menu-parent-item';
		}
	}
	return $items;
}
add_filter( 'wp_nav_menu_objects', 'wpdocs_add_menu_parent_class' );

How to show a placeholder menu if no menu is set up

Credit: Salcode.

If you’ve just installed WordPress and activated a theme, there may not be a primary menu yet set up in Appearance > Menus. For these times you may want to show your own, placeholder, menu until that menu is set up.

To do this, use the fallback callback function. Like so:

wp_nav_menu( array( 'fallback_cb' => 'custom_primary_menu_fallback', 'menu' => 'menu', 'container' => false, 'menu_id' => 'menu', 'menu_class'=>'', 'theme_location'=>'primary-menu' ) );

function custom_primary_menu_fallback() {
  ?>
  <ul id="menu"><li><a href="/">Home</a></li><li><a href="/wp-admin/nav-menus.php">Set primary menu</a></li></ul>
  <?php
}

Simple shortcode for displaying a menu
this will allow you to display a menu in where ever you add the shortcode, lots of room to expand the $args but left it simple.

function get_menu($args){
    $menu = isset($atts['menu']) ? $atts['menu'] : '';
    ob_start();
    wp_nav_menu(array(
        'menu' => $menu
    ) );
    return ob_get_clean();
}
add_shortcode('get_menu', 'get_menu');

Usage Example:

[get_menu menu="Main Menu"]

I’m a little confused about the parameters “before / after” and “link_before / link_after”.

This reference says “before / after” are inside the link, including the link-text, and “link_before / link_after” are outside the link, including the link.

What confuses me:
Some tutorials say, it’s exactly the other way round, (inside / outside):
here and here
I’m coming to the same result, when looking at one of my active WP-installations.

What is correct?

Adding a Word at the Beginning of the Menu

This example will allows you to add the word of your choice to the beginning of your menu as a list item. In this example, the word “Menu:” is added at the beginning. You may want to set an id on the list item (“item-id” in this example) so that you can use CSS to style it.

wp_nav_menu( array(
	'theme_location' => 'primary',
	'items_wrap'     => '<ul><li id="item-id"><?php __( 'Menu:', 'textdomain' ); ?></li>%3$s</ul>'
) );