Contents

• Overview
• Feed Template Files
• Built-in ways to customize feeds
• Customize with custom templates
• Customizing with WP plugns
• Customizing feeds with filters and hooks
• Examples of customizing feeds via functions.php
• Conclusion

Overview of WordPress feeds

• Atom – append /atom/ to any type of feed
• RDF – append /rdf/ to any type of feed
• RSS2 – append /feed/, /feed/rss/, or /feed/rss2/ to just about any WP-generated page (this is the default feed format)

Feed Template files

• /wp-includes/feed-atom.php
• /wp-includes/feed-rdf.php
• /wp-includes/feed-rss.php
• /wp-includes/feed-rss2.php

• /wp-includes/feed-atom-comments.php
• /wp-includes/feed-rss2-comments.php

• http://digwp.com/comments/feed/rdf/
• http://digwp.com/2012/09/notification-list-for-new-books/feed/rdf/

• /wp-includes/feed.php

<item>
	<title>Awesome Video</title>
	<link>http://example.com/awesome-video/</link>
	<comments>http://example.com/awesome-video/#comments</comments>
	<pubDate>Wed, 17 Oct 2012 06:51:07 +0000</pubDate>
	<dc:creator>Perishable</dc:creator>
	<category><![CDATA[WordPress]]></category>
	<guid isPermaLink="false">http://example.com/?p=132</guid>
	<description><![CDATA[Check out this awesome video..]]></description>
	<wfw:commentRss>http://example.com/awesome-video/feed/</wfw:commentRss>
	<slash:comments>500</slash:comments>

	<enclosure url="http://awesome-video.flv" length="104857600" type="video/x-flv" />

</item>

.
.
.
		<wfw:commentRss><?php echo esc_url( get_post_comments_feed_link(null, 'rss2') ); ?></wfw:commentRss>
		<slash:comments><?php echo get_comments_number(); ?></slash:comments>

<?php rss_enclosure(); ?>

	<?php do_action('rss2_item'); ?>
	</item>
	<?php endwhile; ?>
</channel>
</rss>

Built-in ways to customize feeds

Customize with custom templates

1. Create a custom page template – and paste into it any existing feed template
2. Modify the custom feed template – for example, change the number of posts, make it a category-specific feed, add custom XML enclosures, and so on.
3. Provide a link to the feed – once everything is in place, the custom feed will be available at the URL of its custom page.

Customizing with WP plugns

• Comments On Feed – enables visitors to view and leave comments directly from each post in the WordPress content feed.
• Feed Template Customize – enables you to modify WP’s RSS and Atom feeds using your own custom feed-templates.
• RSS Image Feed – adds the first image of a post to your feeds, even in Firefox and even if you only display the excerpt.
• RSS Custom Fields – includes all of your custom fields in your feed so you can pull data out of WordPress and use it elsewhere.
• Custom Post Type RSS feeds – makes it “super easy” to create an RSS feed based on custom post types.

Customizing feeds with filters and hooks

// add custom feed content
function add_feed_content($content) {
	if(is_feed()) {
		$content .= '<p>This article is copyright &copy; '.date('Y').'&nbsp;'.bloginfo('name').'</p>';
	}
	return $content;
}
add_filter('the_excerpt_rss', 'add_feed_content');
add_filter('the_content', 'add_feed_content');

• atom_ns()
• atom_head()
• atom_author()
• atom_enclosure()
• atom_entry()

• rdf_ns()
• rdf_header()
• rdf_item()

• rss2_ns()
• rss2_head()
• rss_enclosure()
• rss2_item()

• atom_ns()
• atom_comments_ns()
• comments_atom_head()
• comment_atom_entry()

• rss2_ns()
• rss2_comments_ns()
• commentsrss2_head()
• commentrss2_item()

Examples of customizing feeds via functions.php

// add icon and logo to Atom feeds
add_action('atom_head','digwp_atom_feed_add_icon');
add_action('comments_atom_head','digwp_atom_feed_add_icon');
function digwp_atom_feed_add_icon() { ?>

	<feed>
		<icon><?php echo get_template_directory_uri(); ?>/images/logo.ico</icon>
		<logo><?php echo get_template_directory_uri(); ?>/images/logo.gif</logo>
	</feed>

<?php }

// add icon and logo to RSS feeds
add_action('rss_head','digwp_rss_feed_add_icon');
add_action('rss2_head','digwp_rss_feed_add_icon');
add_action('commentsrss2_head','digwp_rss_feed_add_icon');
function digwp_rss_feed_add_icon() { ?>

	<image>
		<url><?php echo get_template_directory_uri(); ?>/images/logo.gif</url>
		<title><?php bloginfo_rss('name'); ?></title>
		<link><?php bloginfo_rss('url'); ?></link>
		<width>125</width>
		<height>75</height>
		<description><?php bloginfo('description'); ?></description>
	</image>

<?php }

// add icon and logo to RDF feeds
add_action('rdf_header','digwp_rdf_feed_add_icon');
function digwp_rdf_feed_add_icon() { ?>

	<image rdf:about="<?php echo get_template_directory_uri(); ?>/images/logo.gif">
		<title><?php bloginfo_rss('name'); ?></title>
		<url><?php echo get_template_directory_uri(); ?>/images/logo.gif</url>
		<link><?php bloginfo_rss('url'); ?></link>
		<description><?php bloginfo('description'); ?></description>
	</image>

<?php }

// enable WP automatic feed links
if (function_exists('automatic_feed_links')) {
	automatic_feed_links();
} else {
	return;
}

// remove version info from head and feeds
add_filter('the_generator', 'digwp_complete_version_removal');
function digwp_complete_version_removal() {
	return '';
}

// delay feed update after posting
add_filter('posts_where', 'publish_later_on_feed');
function publish_later_on_feed($where) {
	global $wpdb;
	if (is_feed()) {
		// timestamp in WP-format
		$now = gmdate('Y-m-d H:i:s');

		// value for wait; + device
		$wait = '5'; // integer

		// http://dev.mysql.com/doc/refman/5.0/en/date-and-time-functions.html#function_timestampdiff
		$device = 'MINUTE'; // MINUTE, HOUR, DAY, WEEK, MONTH, YEAR

		// add SQL-sytax to default $where
		$where .= " AND TIMESTAMPDIFF($device, $wpdb->posts.post_date_gmt, '$now') > $wait ";
	}
	return $where;
}

// disable all feeds
function digwp_disable_feed() {
	wp_die(__('<h1>Feed not available, please visit our <a href="'.get_bloginfo('url').'">Home Page</a>!</h1>'));
}
add_action('do_feed',      'digwp_disable_feed', 1);
add_action('do_feed_rdf',  'digwp_disable_feed', 1);
add_action('do_feed_rss',  'digwp_disable_feed', 1);
add_action('do_feed_rss2', 'digwp_disable_feed', 1);
add_action('do_feed_atom', 'digwp_disable_feed', 1);

// customize first feed post only
add_filter('the_content', 'digwp_customize_first_feed_post');
add_filter('the_excerpt', 'digwp_customize_first_feed_post');
function digwp_customize_first_feed_post($content) {
	global $wp_query;
	if (is_feed()) {
		$feed_type = get_query_var('feed');
		if ($wp_query->current_post == 0) {
			return '<p>Put some custom content here!</p>' . $content;
		} else {
			return $content;
		}
	} else { return $content; }
}

Conclusion