Arguments ignored/markup changed in wp_nav_menu if no menu is selected

by

Here’s the default usage of wp_nav_menu():

<?php 
$defaults = array(
  'theme_location'  => ,
  'menu'            => , 
  'container'       => 'div', 
  'container_class' => 'menu-{menu slug}-container', 
  'container_id'    => ,
  'menu_class'      => 'menu', 
  'menu_id'         => ,
  'echo'            => true,
  'fallback_cb'     => 'wp_page_menu',
  'before'          => ,
  'after'           => ,
  'link_before'     => ,
  'link_after'      => ,
  'items_wrap'      => '<ul id=\"%1$s\" class=\"%2$s\">%3$s</ul>',
  'depth'           => 0,
  'walker'          => 
);
?>

Notice that the default fallback for wp_nav_menu() is wp_page_menu(), for which the defaults are:

<?php 
$args = array(
'sort_column' => 'menu_order, post_title',
'menu_class'  => 'menu',
'include'     => '',
'exclude'     => '',
'echo'        => true,
'show_home'   => false,
'link_before' => '',
'link_after'  => '' 
);
?>

These should produce mostly the same output, with the same set of pages. However, if you need more specific control, you have a couple options:

  1. Assign a custom callback here:

    ‘fallback_cb’ => ‘mytheme_wp_nav_menu_cb’

    …and then, define:

      function mytheme_wp_nav_menu_cb() {
      // Output whatever menu you want here
  }

    …so that you override wp_page_menu()

  2. Wrap your wp_nav_menu() call in a has_nav_menu() conditional:

    if ( has_nav_menu( 'my_theme_top_menu' ) ) {
    // User has applied a custom menu
    // to the my_theme_top_menu location;
    // output it
    wp_nav_menu( array( 'theme_location' => 'my_theme_top_menu') );
} else {
    // User has NOT applied a custom menu;
    // Do something else
}

    …in the else statement, you can do whatever.