Add WordPress featured image to RSS feed

Question

I'm setting up an RSS to email campaign in MailChimp using my WordPress RSS Feed, and I want to include the featured image in my MailChimp template. I've tried using this to add the image, which works, but it simply adds it to the content, which doesn't work for MailChimp section of the RSS code:

function featuredtoRSS($content) {
global $post;
if ( has_post_thumbnail( $post->ID ) ){
$content = '' . get_the_post_thumbnail( $post->ID, 'thumbnail', array( 'style' => 'float:left; margin:0 15px 15px 0;' ) ) . '' . $content;
}
return $content;
}

add_filter('the_excerpt_rss', 'featuredtoRSS');
add_filter('the_content_feed', 'featuredtoRSS');

Apparently, MailChimp wants it's "own" unique image element. Here's an example of what they want: http://kb.mailchimp.com/article/how-can-i-format-the-image-content-in-my-rss-to-email-campaigns

but it looks like it's in a different RSS format. Here's what my RSS is outputting: http://pacmissions.org/dev/missions/zimbabwe-2012/feed/

Answer 1

I often have to create custom feeds for MailChimp, and find that a lot of the time I have to make somewhat 'hacky' changes like putting custom values into the limited standard fields that MailChimp supports.

Because of this I like to use the method described at Yoast ( http://yoast.com/custom-rss-feeds-wordpress/ ) to create a page that outputs a custom RSS feed.

There are couple of tweaks to make in order to get the featured image included as a field that MailChimp will recognise.

Firstly, you need to add the Media RSS namespace, which I usually do by adding to the opening <rss> tag:

<rss version="2.0" xmlns:media="http://search.yahoo.com/mrss">

Then in order to include the featured image inside the item:

<?php if(get_the_post_thumbnail()): ?>
    <media:content url="<?php echo wp_get_attachment_url(get_post_thumbnail_id($post->ID)); ?>" medium="image" />
<?php endif; ?>

If you need to specify a particular image size to include, you'll need to use this code inside the item instead:

<?php if(get_the_post_thumbnail()): ?>
    <media:content url="<?php $image = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID), 'imageSize'); echo $image[0]; ?>" medium="image" />
<?php endif; ?>

You can then grab this in MailChimp using the *|RSSITEM:IMAGE|* or *|FEEDITEM:IMAGE|* merge tags.