This idea is not necessarily new but finding an example may be a bit more difficult. Let’s have a look …

First off, there are several sources of information regarding wp_nav_menu() to take into consideration:

Each of these links will open in a new tab/window for convenience purposes.

• The WordPress codex reference.
• The “core.trac.wordpress.org” reference.
• This web site’s references.

Now that we have a list of reading material we should actually take a look at it …

• The first reference leads to the WordPress codex and provides the standard parameters that can be used with wp_nav_menu().
• The next reference and the experience that was offered by Ian Stewart from ThemeShaper.com is the real key to solving this little puzzle.
• The last reference simply leads to the wp_nav_menu() tag archive here.

I would suggest at least having a quick look at those pages before carrying on to the next page, especially the one referencing the wp_nav_menu() function in the “core”, or primary code base of WordPress, as you will find a very relevant comment there.

Let’s start by focusing on the following code snippet as found in the “core” reference:

// Allow plugins to hook into the menu to add their own <li>'s
$items = apply_filters( 'wp_nav_menu_items', $items, $args );
$items = apply_filters( "wp_nav_menu_{$menu->slug}_items", $items, $args );
$nav_menu .= $items;

The beauty of this little snippet is it shows, with the use of the wp_nav_menu_item filter, you can add specific items to the menu output if the end-user has chosen to create a custom menu. Let’s look at an example that will allow you to add a “Home” page link to the beginning of the menu.

If you add the following to your ‘functions.php’ template file it will add a home link to your wp_nav_menu() output:

// Filter wp_nav_menu() to add additional links and other output
function new_nav_menu_items($items) {
	$homelink = '<li class="home"><a href="' . home_url( '/' ) . '">' . __('Home') . '</a></li>';
	$items = $homelink . $items;
	return $items;
}
add_filter( 'wp_nav_menu_items', 'new_nav_menu_items' );

The basic premise of the function is:

1. Assign your desired output to a variable
2. Concatenate the output variable with the $items variable
3. Return the $items variable so it can be used in the filter
4. Add the results of the function to wp_nav_menu_items with an add_filter() function

If you wish to use this when a custom menu is not being used just add the following (or similar) filter after the above code:

add_filter( 'wp_list_pages', 'new_nav_menu_items' );

But what if we wanted to add something to the end of the menu output, such as a RSS feed link, or maybe just some random text or a static URL link. Let’s look at the following example which expands upon the code above to do just that.

// Filter wp_nav_menu() to add additional links and other output
function new_nav_menu_items($items) {
	$homelink = '<li class="home"><a href="' . home_url( '/' ) . '">' . __('Home') . '</a></li>';
	$feedlink = '<li class="feed"><a href="' . get_bloginfo_rss('rss2_url') . '">' . __('RSS') . '</a></li>';
	$random_text = '<li class="rainbows"><a href="#">OMG ... Double Rainbows!</a></li>';
	$items = $homelink . $items;
	$items = $items . $feedlink;
	$items = $items . $random_text;
	return $items;
}
add_filter( 'wp_list_pages', 'new_nav_menu_items' );
add_filter( 'wp_nav_menu_items', 'new_nav_menu_items' );

There always seems to be some new way to add more uses to the core functions in WordPress and I like to find, explore and write about them. I often implement them in the First Aid Theme, as I have done by using the above example code to add a “Home” link to the menu. On the next page I will leave you with one more example, the one I referred to in the opening paragraph.

Although this was a bit more involved it really did not make that much of a difference in the case of implementing this in a custom menu so without further ado here is the code snippet:

function new_nav_menu_items($items) {
  $cat_menu_list = wp_list_categories( 'echo=0&title_li=&child_of=124' );
  $items = $items . $cat_menu_list;
  return $items;
}
add_filter( 'wp_nav_menu_items', 'new_nav_menu_items' );

If you are trying this at home make back-ups of your files, just in case you want to revert your edits. Your category list hierarchy may need to be noted as well.

The key to this snippet is the wp_list_categories() by default will echo its results to the screen, you will have to set the parameter ‘echo=0′ to turn off this default behavior.

As for using this technique for categories with a non-custom menu I will leave that as an exercise for those looking for a challenge … Enjoy!

This post will be dealing with function arguments in common between wp_nav_menu() and wp_page_menu(). Follow-up posts will be covering wp_list_pages() and wp_list_categories(). I will not be covering the specific use for each function’s arguments; the idea is to help show how these options correlate to one another.

Let’s start with the full default of wp_nav_menu() ¹ explicitly displayed:

wp_nav_menu( array(
    'menu'              => '',
    'container'         => 'div',
    'container_class'   => '',
    'container_id'      => '',
    'menu_class'        => 'menu',
    'menu_id'           => '',
    'echo'              => true,
    'fallback_cb'       => 'wp_page_menu',
    'before'            => '',
    'after'             => '',
    'link_before'       => '',
    'link_after'        => '',
    'depth'             => 0,
    'walker'            => '',
    'theme_location'    => ''
    ) );

Followed by the same explicit defaults of wp_page_menu() ^{2, 3}:

wp_page_menu( array(
    'sort_column'       => 'menu_order, post_title',
    'include'           => '',
    'exclude'           => '',
    'show_home'         => false,
    'menu_class'        => 'menu',
    'echo'              => true,
    'link_before'       => '',
    'link_after'        => ''
    ) );

Now onto updating wp_page_menu() to wp_nav_menu(), which turns out to be rather simple.

Here is the break-down of the wp_page_menu() default options from above:

• 'sort_column' – not used
• 'include' – not used
• 'exclude' – not used
• 'show_home' – not used (see bonus section below)
• 'menu_class' – same as wp_nav_menu()
• 'echo' – same as wp_nav_menu()
• 'link_before' – same as wp_nav_menu()
• 'link_after' – same as wp_nav_menu()

First off ‘sort_column’, ‘include’, and ‘exclude’ are replaced by the end-user’s choices using the UI of wp_nav_menu() found under Appearance | Menu in the dashboard. The balance of the default options are the same in wp_nav_menu(), with the exception of 'show_home' => false which is the “bonus” content.

Upgrading from wp_page_menu() to wp_nav_menu() may be as easy as a simple find and replace operation.

Let’s start with an obvious example: a link from the blog title back to the home page.

<a href="http://wpfirstaid.com/">WP First Aid</a>

The above example is very, very basic … let’s dress it up a bit:

<h1 class="blog-title"><a href="http://wpfirstaid.com/" alt="Going Home: WP First Aid">WP First Aid</a></h1>

Now we have a title using the h1 element and a CSS class of blog-title with some alt text letting the reader know where the link will be going. This is better but how does this help you? Let’s make use of WordPress’ built in functions to make this example more generic and easily transferable.

<h1 class="blog-title"><a href="<?php bloginfo('url'); ?>" alt="Going Home: <?php bloginfo('name'); ?>"><?php bloginfo('name'); ?></a></h1>

This example makes use of the WordPress function bloginfo(). Here is a link to the WordPress codex for this function; and, here is a link to the get_bloginfo() function which provides additional details.

Our next example is adding a home page link to a navigation bar. Many navigation bars are generated with one of three WordPress functions: wp_list_pages(), wp_page_menu(), or wp_list_categories(). The wp_page_menu function uses a value that creates a home page link, for example:

<?php wp_page_menu('show_home=1'); ?>

The wp_page_menu function includes all the available parameters of the wp_list_pages function and also includes wrapping the output in an unordered list.

To add a home page link into a theme using the wp_list_pages function you may look at the following example for guidance:

<ul>
  <li><a href="<?php bloginfo('url'); ?>" alt="Going Home: <?php bloginfo('name'); ?>"><?php bloginfo('name'); ?></a></li>
  <?php wp_list_pages(); ?>
</ul>

Adding a home page link to a navigation menu created with the wp_list_categories function is very similar. Let’s take a quick look at it below.

<ul>
  <li><a href="<?php bloginfo('url'); ?>" alt="Going Home: <?php bloginfo('name'); ?>"><?php bloginfo('name'); ?></a></li>
  <?php wp_list_categories(); ?>
</ul>

The only difference in the above two examples are the function call. The links we added to the home page are almost identical to the the link example we used for the blog title.

Feel free to use any of the above examples in your own works. Of course, there could be additional CSS elements needed to work with your theme’s style but I will leave that as an exercise for you … or feel free to contact us with more complex code requirements.