WP_NAV_MENU filter targets all menus

Question

Im trying to replace my template's primary menu through a plugin so that I don't have to make changes to the header.php.

I found this code in another question answered here in 2011 (Replacing WordPress menu functionality with a plugin)

add_filter('wp_nav_menu', 'my_menu_func');
function my_menu_func(){
  print "Testing 123";
}

It worked but it replaced both my top primary menu and the widget side menu.

How can I specify which menu to target when using the filter?

Answer 1

You could try the following code snippet to override the primary menu:

/**
 * Override the primary menu.
 *
 * @param string  $nav_menu The HTML content for the navigation menu.
 * @param array   $args     Array of wp_nav_menu() arguments.
 * @return string $nav_menu
 */

function wpse_150003( $nav_menu, $args )
{
    //Override the primary menu:
    if( 'primary' === $args->theme_location )
        $nav_menu = 'My new menu';

    return $nav_menu;
}

add_filter( 'wp_nav_menu', 'wpse_150003', PHP_INT_MAX, 2 );

where we find the input arguments info from the source.

Notice that we return the $nav_menu value, instead of echoing it.

You could also filter my other attributes, for example menu_id.

You might also consider these filters:

• wp_nav_menu_items
• wp_nav_menu_{$menu->slug}_items

I hope this helps.