custom-walker.php

<?php

if ( ! class_exists( 'WP_Custom_Walker' ) ) {
	/**
	 * WP_Custom_Walker class.
	 *
	 * @extends Walker_Nav_Menu
	 */
	class WP_Custom_Walker extends Walker_Nav_Menu {

		public function start_lvl( &$output, $depth = 0, $args = array() ) {
			if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
				$t = '';
				$n = '';
			} else {
				$t = "\t";
				$n = "\n";
			}
			$indent = str_repeat( $t, $depth );

			// Default class.
			$classes = array( 'navbar-dropdown' );

			$class_names = join( ' ', apply_filters( 'nav_menu_submenu_css_class', $classes, $args, $depth ) );
			$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

			$output .= "{$n}{$indent}<div$class_names>{$n}";
		}

		public function end_lvl( &$output, $depth = 0, $args = array() ) {
			if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
				$t = '';
				$n = '';
			} else {
				$t = "\t";
				$n = "\n";
			}
			$indent = str_repeat( $t, $depth );
			$output .= "$indent</div></div>{$n}";
		}

		public function start_el( &$output, $item, $depth = 0, $args = array(), $id = 0 ) {
			if ( isset( $args->item_spacing ) && 'discard' === $args->item_spacing ) {
				$t = '';
				$n = '';
			} else {
				$t = "\t";
				$n = "\n";
			}
			$indent = ( $depth ) ? str_repeat( $t, $depth ) : '';

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

			$args = apply_filters( 'nav_menu_item_args', $args, $item, $depth );

			$class_names = join( ' ', apply_filters( 'nav_menu_css_class', array_filter( ['navbar-item', 'has-dropdown'] ), $item, $args, $depth ) );
			$class_names = $class_names ? ' class="' . esc_attr( $class_names ) . '"' : '';

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

			$is_child = false;

			if($this->has_children) {
				$output .= $indent . '<div' . $id . $class_names . '>';
				$is_child = true;
			}

			$atts = array();
			$atts['title']  = ! empty( $item->attr_title ) ? $item->attr_title : '';
			$atts['target'] = ! empty( $item->target )     ? $item->target     : '';
			$atts['rel']    = ! empty( $item->xfn )        ? $item->xfn        : '';
			$atts['href']   = ! empty( $item->url )        ? $item->url        : '';
			if($is_child){
				$atts['class']   = 'navbar-link';
			} else {
				$atts['class']   = 'navbar-item';
			}

			$atts = apply_filters( 'nav_menu_link_attributes', $atts, $item, $args, $depth );

			$attributes = '';
			foreach ( $atts as $attr => $value ) {
				if ( ! empty( $value ) ) {
					$value = ( 'href' === $attr ) ? esc_url( $value ) : esc_attr( $value );
					$attributes .= ' ' . $attr . '="' . $value . '"';
				}
			}

			$title = apply_filters( 'the_title', $item->title, $item->ID );

			$title = apply_filters( 'nav_menu_item_title', $title, $item, $args, $depth );

			$item_output = $args->before;
			$item_output .= '<a'. $id . $attributes .'>';
			$item_output .= $args->link_before . $title . $args->link_after;
			$item_output .= '</a>';
			$item_output .= $args->after;

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

		public function end_el( &$output, $item, $depth = 0, $args = array() ) {}
	}
}