Bootstrap 4 navwalker - multilevel menu - php

Question

I'm using this nav walker in my Wordpress project. I want to create multilevel menu, for example. What I need to change to get it work? Or maybe is it another walker for BS4 with multilevel menu support?
Menu Item
- Sub menu
-- Sub menu item
-- Sub menu item
Menu Item

Answer 1

Add this css
ul.dropdown-menu li > ul.dropdown-menu{
left: 100%;
top: 0;
}
ul.dropdown-menu li:hover > ul.dropdown-menu, ul.dropdown-menu li:focus > ul.dropdown-menu{
display: block
}
Remove this code && 0 === $depth from class-wp-bootstrap-navwalker.php
original code:
if ( isset( $args->has_children ) && $args->has_children && 0 === $depth && $args->depth > 1 ) {
After editing:
if ( isset( $args->has_children ) && $args->has_children && $args->depth > 1 ) {

Answer 2

Bulding simple menu list - here in user contributed notes (1st one) you can find code for build menu using menu array data, its simple and can be modified as you need.
Here is the code:
<?php
// Intented to use bootstrap 3.
// Location is like a 'primary'
// After, you print menu just add create_bootstrap_menu("primary") in your
preferred position;
#add this function in your theme functions.php
function create_bootstrap_menu( $theme_location ) {
if ( ($theme_location) && ($locations = get_nav_menu_locations()) && isset($locations[$theme_location]) ) {
$menu_list = '<nav class="navbar navbar-default">' ."\n";
$menu_list .= '<div class="container-fluid">' ."\n";
$menu_list .= '<!-- Brand and toggle get grouped for better mobile display -->' ."\n";
$menu_list .= '<div class="navbar-header">' ."\n";
$menu_list .= '<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">' ."\n";
$menu_list .= '<span class="sr-only">Toggle navigation</span>' ."\n";
$menu_list .= '<span class="icon-bar"></span>' ."\n";
$menu_list .= '<span class="icon-bar"></span>' ."\n";
$menu_list .= '<span class="icon-bar"></span>' ."\n";
$menu_list .= '</button>' ."\n";
$menu_list .= '<a class="navbar-brand" href="' . home_url() . '">' . get_bloginfo( 'name' ) . '</a>';
$menu_list .= '</div>' ."\n";
$menu_list .= '<!-- Collect the nav links, forms, and other content for toggling -->';
$menu = get_term( $locations[$theme_location], 'nav_menu' );
$menu_items = wp_get_nav_menu_items($menu->term_id);
$menu_list .= '<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">' ."\n";
$menu_list .= '<ul class="nav navbar-nav">' ."\n";
foreach( $menu_items as $menu_item ) {
if( $menu_item->menu_item_parent == 0 ) {
$parent = $menu_item->ID;
$menu_array = array();
foreach( $menu_items as $submenu ) {
if( $submenu->menu_item_parent == $parent ) {
$bool = true;
$menu_array[] = '<li>' . $submenu->title . '</li>' ."\n";
}
}
if( $bool == true && count( $menu_array ) > 0 ) {
$menu_list .= '<li class="dropdown">' ."\n";
$menu_list .= '' . $menu_item->title . ' <span class="caret"></span>' ."\n";
$menu_list .= '<ul class="dropdown-menu">' ."\n";
$menu_list .= implode( "\n", $menu_array );
$menu_list .= '</ul>' ."\n";
} else {
$menu_list .= '<li>' ."\n";
$menu_list .= '' . $menu_item->title . '' ."\n";
}
}
// end <li>
$menu_list .= '</li>' ."\n";
}
$menu_list .= '</ul>' ."\n";
$menu_list .= '</div>' ."\n";
$menu_list .= '</div><!-- /.container-fluid -->' ."\n";
$menu_list .= '</nav>' ."\n";
} else {
$menu_list = '<!-- no menu defined in location "'.$theme_location.'" -->';
}
echo $menu_list;
}
?>