Come creare un nuovo feed RSS personalizzato su WordPress

Questo rapido codice installato nel file functions.php del tuo sito WordPress ti aiuterà a creare un nuovo feed RSS personalizzato con i campi che ti servono.

add_action('init', 'customRSS');
 function customRSS(){
         add_feed('feedformailup', 'customRSSFunc');
 }
 function customRSSFunc(){
         get_template_part('rss', 'feedformailup');
}

file che si chiama rss-feedformailup.php
<?php
 /**
 * Template Name: Custom RSS Template - Feedname
 */
 $postCount = 5; // The number of posts to show in the feed
 $posts = query_posts('showposts=' . $postCount);
 header('Content-Type: '.feed_content_type('rss-http').'; charset='.get_option('blog_charset'), true);
 echo '<?xml version="1.0" encoding="'.get_option('blog_charset').'"?'.'>';
 ?>
 <rss version="2.0"
         xmlns:content="http://purl.org/rss/1.0/modules/content/"
         xmlns:wfw="http://wellformedweb.org/CommentAPI/"
         xmlns:dc="http://purl.org/dc/elements/1.1/"
         xmlns:atom="http://www.w3.org/2005/Atom"
         xmlns:sy="http://purl.org/rss/1.0/modules/syndication/"
         xmlns:slash="http://purl.org/rss/1.0/modules/slash/"
         <?php do_action('rss2_ns'); ?>>
 <channel>
         <title><?php bloginfo_rss('name'); ?></title>
         <atom:link href="<?php self_link(); ?>" rel="self" type="application/rss+xml" />
         <link><?php bloginfo_rss('url') ?></link>
         <description><?php bloginfo_rss('description') ?></description>
         <lastBuildDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_lastpostmodified('GMT'), false); ?></lastBuildDate>
         <language><?php echo get_option('rss_language'); ?></language>
         <sy:updatePeriod><?php echo apply_filters( 'rss_update_period', 'hourly' ); ?></sy:updatePeriod>
         <sy:updateFrequency><?php echo apply_filters( 'rss_update_frequency', '1' ); ?></sy:updateFrequency>
         <?php do_action('rss2_head'); ?>
         <?php while(have_posts()) : the_post(); ?>
                 <item>
                         <title><?php echo simple_my_excerpt(get_the_title(),15); ?></title>
                               <content><?php echo wp_get_attachment_url( get_post_thumbnail_id($post->ID) ) ?></content>
                         <link><?php the_permalink_rss(); ?></link>
                         <pubDate><?php echo mysql2date('D, d M Y H:i:s +0000', get_post_time('Y-m-d H:i:s', true), false); ?></pubDate>
                         <dc:creator><?php the_author(); ?></dc:creator>
                         <guid isPermaLink="false"><?php the_guid(); ?></guid>
                         <description><![CDATA[<?php echo simple_my_excerpt(get_the_excerpt(),20); ?>]]></description>
                         <content:encoded><![CDATA[<?php the_excerpt_rss() ?>]]></content:encoded>
                         <?php rss_enclosure(); ?>
                         <?php do_action('rss2_item'); ?>
                 </item>
         <?php endwhile; ?>
 </channel>
</rss>