How to append something before final </ul> tag in walker class?

Question

Here is the real picture I want to produce.

 <ul>
    <li>
        <ul>
            <li> </li>
            <li> </li>
           ###NOT HERE ###
        </ul>
     </Ii>
    ###I want to add some html here ###
</ul>

I am trying as follows:

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".get_search_form(false)."</ul>{$n}";
}

But it appended the search box at the end of every sub menu(###NOT HERE ### section). How can I achieve the desired output. Any idea?

Answer 1

You should check the $depth argument to make sure the search form only appears at a certain depth/level, e.g. if( 0 === $depth ) { ... }

I personally would place the search form outside the <ul> though as I don't think it's valid HTML. It would hurt your site's accessibility. Alternatively, wrap it in a <li></li> so it's a proper list item.

Answer 2

I apply this trick to filter the menu:

add_filter('wp_nav_menu_items','add_search_box_to_menu', 10, 2);
    function add_search_box_to_menu( $items, $args ) {
        if( $args->theme_location == 'primary' )
            return $items."<li class='menu-header-search'><form action='http://example.com/' id='searchform' method='get'><input type='text' name='s' id='s' placeholder='Search'></form></li>";

        return $items;
    }