Wordpress change wp_nav_menu walker with a custom one

Question

I have a downloaded theme and it where the wp_nav_menu is created it looks something like this:

<div class="nv-nav-wrap">
    <div role="navigation" class="<?php echo esc_attr( join( ' ', $container_classes ) ); ?>"
            aria-label="<?php esc_attr_e( 'Primary Menu', 'neve' ); ?>">

        <?php
        echo wp_nav_menu(
            [
                'theme_location' => 'primary',
                'menu_id'        => $menu_id,
                'menu_class'     => 'primary-menu-ul nav-ul' . $additional_menu_class,
                'container'      => 'ul',
                'walker'         => '\Neve\Views\Nav_Walker',
                'fallback_cb'    => '\Neve\Views\Nav_Walker::fallback',
                'echo'           => false,
            ]
        );
        ?>
    </div>
</div>

I've created a child theme and I want to change the walker of the wp_nav_menu. How can I do that? The new walker's name is "Aria walker Nav menu" (just for reference)

I've tried putting this in functions.php in the child theme:

    wp_nav_menu( array(
      'theme_location' => 'primary',
      'container'      => false,
      'menu_class'     => 'primary-menu-ul nav-ul',
      'walker'         => new Aria_Walker_Nav_Menu(),
      'items_wrap'     => '<ul id="%1$s" class="%2$s">%3$s</ul>',
    ) );

But it creates a whole new menu. How do I just replace the walker for the original one in the theme

Answer 1

In general you'd add child substitutions for the relevant templates if possible, as Tom mentions in the comments.

Alternately, you can use a wp_nav_menu_args filter hook to swap in your own arguments prior to WordPress retrieving and rendering the menu:

add_filter( 'wp_get_nav_menu_args', 'wpse406010_primary_nav_menu_args' );

function wpse406010_primary_nav_menu_args( $args ) {
  if( $args[ 'theme_location' ] !== 'primary' || $args[ 'walker' ] !== '\Neve\Views\Nav_Walker' )
    return $args;

  $args[ 'container' ]  = false;
  $args[ 'menu_class' ] = 'primary-menu-ul nav-ul';
  $args[ 'walker' ]     = new Aria_Walker_Nav_Menu();
  $args[ 'items_wrap' ] = '<ul id="%1$s" class="%2$s">%3$s</ul>';

  return $args;
}