List subpage of subpage

Question

I've got a site with the following structure:

About

• Page 1
• Page 2
• Page 3
  • Page 3.1
  • Page 3.2

So Page 1, Page 2,... are subpages of the About page. I would like to have a sidebar that lists the pages, but only shows the subpages when needed. So when I'm on Page 1, I need to see:

• Page 1
• Page 2
• Page 3

And when I'm on Page 3 I need to see:

• Page 1
• Page 2
• Page 3
  • Page 3.1
  • Page 3.2

Also, when I'm on Page 3.1 or 3.2 I'd like to see the same thing. I've got following code so far:

<?php
  if($post->post_parent)
  $children = wp_list_pages("title_li=&child_of=".$post->post_parent."&echo=0&depth=1");
  else
  $children = wp_list_pages("title_li=&child_of=".$post->ID."&echo=0&depth=1");
  if ($children) { ?>
  <ul>
  <?php echo $children; ?>
  </ul>
  <?php } ?> 

But when I'm on Page 3 now, the subpages don't get listed. I've tried adapting the code in various ways, but either the subpages don't get listed, or the parent pages or siblings don't display... Anyone has a suggestion or a solution about this one? Thanks.

Answer 1

Here is a function that im using for submenus, maybe there is a better way to do this but i always ends up with this solution. Add this function to your theme functions.php file:

function wpse_submenu( $id, $echo = false, $showParent = true, $depth = 0 ) {
    global $wpdb, $post, $before, $page_for_posts;

    // if is a page
    if( get_post_type() == 'post' || is_paged() ) {
        $id = get_option('page_for_posts');
    }

    $the_post_ID = $id;
    $page_id = get_page( $id );
    _get_post_ancestors( $page_id );
    $ancestors = array_filter( $page_id->ancestors );
    $parent_id = count( $ancestors ) > 0 ? $ancestors[ count( $ancestors ) - 1] : $id;

    $post->ID = $id;

    $page_query = get_page( $parent_id );
    $parent_title = $page_query->post_title;
    $page_menu = wp_list_pages(' echo=0&depth='. $depth .'&title_li=&child_of='. $parent_id );

    wp_reset_query();

    // echo or not
    if( $echo ){
        $sub_pages = explode( "\n", $page_menu );

        // add class first and last class
        $last = (count( $sub_pages ) - 2);
        $sub_pages[0] = str_replace( 'class="', 'class="first ', $sub_pages[0] );           // first
        $sub_pages[$last] = str_replace( 'class="', 'class="last ', $sub_pages[$last] );    // last

        // if the parent is the current page
        if( $the_post_ID == $parent_id ){
            $class = " current_page_item";
        } else {
            $class = "";
        }

        echo '<ul class="pagenav">';

            // if to show the parent in the menu
            if( $showParent ){
                echo '<li class="parent-page page_item'. $class .'" ><a href="'. get_permalink( $parent_id ) .'">'. $parent_title .'</a></li>';
            }

            // echo all the pages
            foreach( $sub_pages as $page ){
                echo $page ."\n";
            }

        echo '</ul>';
    } else {
        return $page_menu;
    }
}

And put this where you want the submenu to bee displayed:

<?php if( wpse_submenu( $post->ID ) ) wpse_submenu( $post->ID, true, false ); ?>

And som basic css that will hide the subpages when on the first level:

.pagenav ul {
    display: none;
}
.pagenav .current_page_parent .children,
.pagenav .current_page_ancestor .children,
.pagenav .current_page_item .children {
    display: block;
}