How can I modify RSS item titles to be either the title or a custom meta field?

Question

I'd like to optionally replace some RSS item titles with a headline meta field I've added to certain post types.

I have the post types showing up in the feed using:

function myfeed_request($qv) {
  if (isset($qv['feed']) && !isset($qv['post_type']))
    $qv['post_type'] = array('post', 'interviews', 'reviews');
  return $qv;
}
add_filter('request', 'myfeed_request');

But I've searched around and can't figure out how to replace the title. Any ideas?

Answer 1

Something like this (not tested):

add_filter('the_title_rss', 'custom_feed_title');

function custom_feed_title($title) {

    $headline = get_post_meta(get_the_id(), 'headline', true);

    if (!empty($headline))
        return $headline;

    return $title;
}