Question

I have 2 websites, and I wish to show some posts from one on the other using an RSS feed.

Trouble is, the default seems to be order by publish date, where as I need them ordered by title. I’m using WordPress, which uses SimplePie (which I believe is pretty common?).

Is there a way to reorder these items before I display them? Thanks.

/**
 * $feed = the RSS feed to display (set via CMS option)
 * $num_posts = the number of posts to display from the feed (set via CMS option)
 */
$max_items = 0;
if($feed !== '') :
    $rss = fetch_feed($feed);
    if(!is_wp_error($rss)) :
        $max_items = $rss->get_item_quantity($num_posts);
        $rss_items = $rss->get_items(0, $max_items);
    endif;
endif;

Answer 1

Okey, so I’ve come up with an answer that seems to work.

require_once(ABSPATH . WPINC . '/class-feed.php');
require_once(ABSPATH . WPINC . '/class-simplepie.php');

class SimplePie_Custom_Sort extends SimplePie{

    /**
     * @var string How to order the feed
     * @access private
     */
    var $order_feed_by;

    /**
     * Sort the items that are to be displayed in an RSS feed
     */
    function sort_items($a, $b){

        /** Construct the sort function name */
        $sort_function = 'sort_items_'.$this->order_feed_by;

        /** Check if the sort function exists and call it (call 'parent::sort_items' if not) */
        if(method_exists($this, $sort_function)) :
            $this->$sort_function($a, $b);
        else :
            parent::sort_items($a, $b);
        endif;

    }

    /**
     * Sort function to sort posts in an RSS feed by title
     */
    function sort_items_title($a, $b){

        return $b->get_title() <= $a->get_title();

    }

}

function fetch_feed_custom($url, $order_by){

    $feed = new SimplePie_Custom_Sort();
    $feed->order_feed_by = $order_by;
    $feed->set_feed_url($url);
    $feed->set_cache_class('WP_Feed_Cache');
    $feed->set_file_class('WP_SimplePie_File');
    $feed->set_cache_duration(apply_filters('wp_feed_cache_transient_lifetime', 43200, $url));
    do_action_ref_array( 'wp_feed_options', array( &$feed, $url ) );
    $feed->init();
    $feed->handle_content_type();

    if($feed->error()) :
        return new WP_Error('simplepie-error', $feed->error());
    endif;

    return $feed;

}