WordPress Snippets at WPcustoms

Use wp_list_pages custom walker to show only post thumbnails

In this example the project required the featured image thumbnail to display in the menu for every page, so rather than displaying a list of links to pages, there is a menu of images. An advanced function which extends the walker class.


/**
 * Snippet Name: Use wp_list_pages custom walker to show only post thumbnails
 * Snippet URL: http://www.wpcustoms.net/snippets/custom-walker-post-thumbnails/
 */
 // create our custom thumbnail walker
class Thumbnail_walker extends Walker_page {
        function start_el(&$output, $page, $depth, $args, $current_page) {
        if ( $depth )
            $indent = str_repeat("\t", $depth);
        else
            $indent = '';
 
        extract($args, EXTR_SKIP);
        $css_class = array('page_item', 'page-item-'.$page->ID);
        if ( !empty($current_page) ) {
            $_current_page = get_page( $current_page );
            _get_post_ancestors($_current_page);
            if ( isset($_current_page->ancestors) && in_array($page->ID, (array) $_current_page->ancestors) )
                $css_class[] = 'current_page_ancestor';
            if ( $page->ID == $current_page )
                $css_class[] = 'current_page_item';
            elseif ( $_current_page && $page->ID == $_current_page->post_parent )
                $css_class[] = 'current_page_parent';
        } elseif ( $page->ID == get_option('page_for_posts') ) {
            $css_class[] = 'current_page_parent';
        }
 
        $css_class = implode( ' ', apply_filters( 'page_css_class', $css_class, $page, $depth, $args, $current_page ) );
 // here comes the fun part where we insert our featured post image sized at 80x80px
        $output .= $indent . '
  • ' . $link_before . apply_filters( 'the_title', '' ) . $link_after . get_the_post_thumbnail($page->ID, array(80,80)) .''; if ( !empty($show_date) ) { if ( 'modified' == $show_date ) $time = $page->post_modified; else $time = $page->post_date; $output .= " " . mysql2date($date_format, $time); } } } // grab the original wp_list_pages function and rename it to keep defaults working function thumbnail_pages($args = '') { $defaults = array( 'depth' => 0, 'show_date' => '', 'date_format' => get_option('date_format'), 'child_of' => 0, 'exclude' => '', 'title_li' => __('Pages'), 'echo' => 1, 'authors' => '', 'sort_column' => 'menu_order, post_title', 'link_before' => '', 'link_after' => '', 'walker' => '', ); $r = wp_parse_args( $args, $defaults ); extract( $r, EXTR_SKIP ); $output = ''; $current_page = 0; // sanitize, mostly to keep spaces out $r['exclude'] = preg_replace('/[^0-9,]/', '', $r['exclude']); // Allow plugins to filter an array of excluded pages (but don't put a nullstring into the array) $exclude_array = ( $r['exclude'] ) ? explode(',', $r['exclude']) : array(); $r['exclude'] = implode( ',', apply_filters('wp_list_pages_excludes', $exclude_array) ); // Query pages. $r['hierarchical'] = 0; $pages = get_pages($r); if ( !empty($pages) ) { if ( $r['title_li'] ) $output .= '
  • '; } $output = apply_filters('wp_list_pages', $output, $r); if ( $r['echo'] ) echo $output; else return $output; } // usage: $thumbmenu = new Thumbnail_walker(); $defaults = array( 'depth' => 0, 'show_date' => '', 'date_format' => get_option('date_format'), 'child_of' => 0, 'exclude' => '', 'title_li' => __('Pages'), 'echo' => 1, 'authors' => '', 'sort_column' => 'menu_order, post_title', 'link_before' => '', 'link_after' => '', 'walker' => $thumbmenu, // this fires our new thumbnail walker menu );