WordPress Walker Code

walker.php

<?php
/* I'm not so certain this works right anymore, but some may find it useful. See https://www.twistermc.com/36600/wordpress-mega-menu/ for full details. */

class description_walker extends Walker_Nav_Menu {
    protected $topLevelId = NULL;
    protected $topLevelCount = NULL;
    protected $templateURL = NULL;

    function description_walker() {
        $this->templateURL = get_theme_root() . '/' . get_template() . '/';
    }

    function start_el(&$output, $item, $depth, $args) {
        global $wp_query;

        $indent = ( $depth ) ? str_repeat( "\t", $depth ) : '';
        $class_names = $value = '';

        if ($depth == 0)
            $this->topLevelId = $item->ID;

        $classes = empty( $item->classes ) ? array() : (array) $item->classes;

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

        $output .= $indent . '<li id="menu-item-'. $item->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        ) .'"' : '';
        $attributes .= ' class= "main-link"';


        $prepend = ''; // top level
        $append = '';  // top level
        $description  = '';

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

        if ($this->topLevelId == 8675309) {
            ob_start();
            require $this->templateURL . '/dropDown1.php';
            $item_output .= ob_get_contents();
            ob_end_clean();
        }

        $item_output .= $args->after;
        $output .= apply_filters( 'walker_nav_menu_start_el', $item_output, $item, $depth, $args );
        $output .= '</li>';
    }
}