How to add class and element to <a>-tag in sub-menu of "wp_nav_menu" in WordPress?

Question

i want to add a class to the a tag of an sub-menu and a b tag inside the link.

WordPress gives me this code:

<li id="menu-item-72" class="menu-item menu-item-type-post_type menu-item-object-page dropdown menu-item-72"><a
    href="#">Link</a>
  <ul class="dropdown-menu"></ul>

And i want this:

<li id="menu-item-72" class="menu-item menu-item-type-post_type menu-item-object-page dropdown menu-item-72"> <a
    href="#" class="dropdown-toggle" data-toggle="dropdown">Link <b class="caret"></b></a>
  <ul class="dropdown-menu"></ul>

Does anybody know a solution for that?

Answer 1

Look at this answer, it explains how to add custom HTML to the wordpress menus: https://stackoverflow.com/a/12251157/1627227

EDIT:

I've put together an example to fit your question. You can place it into functions.php. Note the comments, they explain where to add your custom code.

class Custom_Walker_Nav_Menu extends Walker_Nav_Menu {

  function start_lvl(&$output, $depth) {
      $indent = str_repeat("\t", $depth);
      //$output .= "\n$indent<ul class=\"sub-menu\">\n";

      // Change sub-menu to dropdown menu
      $output .= "\n$indent<ul class=\"dropdown-menu\">\n";
  }

  function start_el ( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
    // Most of this code is copied from original Walker_Nav_Menu
    global $wp_query, $wpdb;
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';

    $class_names = $value = '';

    $classes = empty( $item->classes ) ? array() : (array) $item->classes;
    $classes[] = 'menu-item-' . $item->ID;

    $class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( $classes ), $item, $args ) );
    $class_names = ' class="' . esc_attr( $class_names ) . '"';

    $id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
    $id = strlen( $id ) ? ' id="' . esc_attr( $id ) . '"' : '';

    $has_children = $wpdb->get_var("SELECT COUNT(meta_id)
                            FROM wp_postmeta
                            WHERE meta_key='_menu_item_menu_item_parent'
                            AND meta_value='".$item->ID."'");

    $output .= $indent . '<li' . $id . $value . $class_names .'>';

    $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        ) .'"' : '';

    // Check if menu item is in main menu
    if ( $depth == 0 && $has_children > 0  ) {
        // These lines adds your custom class and attribute
        $attributes .= ' class="dropdown-toggle"';
        $attributes .= ' data-toggle="dropdown"';
    }

    $item_output = $args->before;
    $item_output .= '<a'. $attributes .'>';
    $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;

    // Add the caret if menu level is 0
    if ( $depth == 0 && $has_children > 0  ) {
        $item_output .= ' <b class="caret"></b>';
    }

    $item_output .= '</a>';
    $item_output .= $args->after;

    $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
  }

}

After you have this in place, you have to go to the point where your menu (wp_nav_menu()) is called. In the answer I've linked to, there's the full function call to wp_nav_menu. However you'll have to add this line: 'walker' => new Custom_Walker_Nav_Menu to the arguments array, to use your custom walker object on that specific menu.

Hope you got it ;)

Answer 2

You can place it into functions.php.

class My_Walker_Nav_Menu extends Walker_Nav_Menu {
    function display_element( $element, &$children_elements, $max_depth, $depth=0, $args, &$output ){
      $GLOBALS['dd_children'] = ( isset($children_elements[$element->ID]) )? 1:0;
      $GLOBALS['dd_depth'] = (int) $depth;
      parent::display_element( $element, $children_elements, $max_depth, $depth, $args, $output );
    }
   function start_lvl(&$output, $depth) {
     $indent = str_repeat("\t", $depth);
     $output .= "\n$indent<ul class=\"dropdown-menu\">\n";
   }
  function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) 
  {
    global $wp_query, $wpdb;
    $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';
    $li_attributes = '';
    $class_names = $value = '';
    $classes = empty( $item->classes ) ? array() : (array) $item->classes;

    //Add class and attribute to LI element that contains a submenu UL.
    if ($args->has_children){
      $classes[]    = 'dropdown';
      $li_attributes .= 'data-dropdown="dropdown"';
    }
    $classes[] = 'menu-item-' . $item->ID;
    //If we are on the current page, add the active class to that menu item.
    $classes[] = ($item->current) ? 'active' : '';
    //Make sure you still add all of the WordPress classes.
    $class_names = join( ' ', apply_filters( 'nav_menu_css_class',     array_filter( $classes ), $item, $args ) );
    $class_names = ' class="' . esc_attr( $class_names ) . '"';
    $id = apply_filters( 'nav_menu_item_id', 'menu-item-'. $item->ID, $item, $args );
    $id = strlen( $id ) ? ' id="' . esc_attr( $id ) . '"' : '';
    $has_children = $wpdb->get_var(
    $wpdb->prepare("
       SELECT COUNT(*) FROM $wpdb->postmeta
       WHERE meta_key = %s
       AND meta_value = %d
       ", '_menu_item_menu_item_parent', $item->ID)
     );
   $output .= $indent . '<li' . $id . $value . $class_names .'>';
   $output .= $indent . '<li' . $id . $value . $class_names . $li_attributes . '>';
   //Add attributes to link element.
   $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        ) .'"' : '';
   // Check if menu item is in main menu

if ( $depth == 0 && $has_children > 0  ) {
    // These lines adds your custom class and attribute
    $attributes .= ' class="dropdown-toggle"';
    $attributes .= ' data-toggle="dropdown"';
}
   $item_output = $args->before;
   $item_output .= '<a'. $attributes .'>';
   $item_output .= $args->link_before . apply_filters( 'the_title', $item->title, $item->ID ) . $args->link_after;
   // Add the caret if menu level is 0
   if ( $depth == 0 && $has_children > 0  ) {
      $item_output .= ' <b class="caret"></b>';
   }
   $item_output .= '</a>';
   $item_output .= $args->after;
   $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
  }
}

Then in your template where you want to display this menu place this code.

   <?php

                if ( has_nav_menu( 'primary' ) ) {

                     $defaults = array(
                        'theme_location'  => 'primary',
                        //'menu'            => '',
                         'container'       => 'ul',
                         'container_class' => '',
                         'container_id'    => '',
                         'menu_class'      => '',
                         'menu_id'         => '',
                         'walker'          =>  new My_Walker_Nav_Menu()
                    );

                    wp_nav_menu( $defaults );

                }
            ?> 

Using this I solved my problem.

Answer 3

You can use this to check if there's a sub-menu:

$has_children = $wpdb->get_var("SELECT COUNT(meta_id)
                                FROM wp_postmeta
                                WHERE meta_key='_menu_item_menu_item_parent'
                                AND meta_value='".$item->ID."'");

then do simple checks

if ( $has_children > 0 ) {
  // These lines adds your custom class and attribute
  $attributes .= ' class="dropdown-toggle"';
  $attributes .= ' data-toggle="dropdown"';
}

Remember to set $wpdb as global:

global $wp_query, $wpdb;

Tada~

Answer 4

Use This Code In Function.php

function add_menuclass($ulclass) {
   return preg_replace('/<a /', '<a class="list-group-item"', $ulclass);
}
add_filter('wp_nav_menu','add_menuclass');

Answer 5

Since Wordpress 3.6.0 you can use the nav_menu_link_attributes filter:

add_filter( 'nav_menu_link_attributes', 'add_class_to_items_link', 10, 3 );

function add_class_to_items_link( $atts, $item, $args ) {
  // check if the item has children
  $hasChildren = (in_array('menu-item-has-children', $item->classes));
  if ($hasChildren) {
    // add the desired attributes:
    $atts['class'] = 'dropdown-toggle';
    $atts['data-toggle'] = 'dropdown';
    $atts['data-target'] = '#';
  }
  return $atts;
}

The tags unfortunately doesn't have a filter that we could use, so we'll need a walker:

class MY_Menu_Walker extends Walker_Nav_Menu {

  public function start_lvl( &$output, $depth = 0, $args = array() ) {
    $indent = str_repeat("\t", $depth);
    $output .= "\n$indent<ul class=\"sub-menu dropdown-menu\">\n";
  }   

}

then add the walker option when calling the menu:

wp_nav_menu( array('walker' => new MY_Menu_Walker));