WordPress has built-in the SimplePie RSS parsing engine, making it very easy to display the content of an RSS feed in your theme.
The fetch_feed() function provides access to SimplePie in WordPress, but it’s not that re-usable. I frequently used this handy function for parsing RSS feeds within WordPress themes (or plugins).
A Re-usable RSS Parsing function for WordPress
Place this function in your functions.php file.
/*
* Re-usable RSS feed reader with shortcode
*/
if ( !function_exists('base_rss_feed') ) {
function base_rss_feed($size = 5, $feed = 'https://wordpress.org/news/feed/', $date = false, $cache_time = 1800)
{
// Include SimplePie RSS parsing engine
include_once ABSPATH . WPINC . '/feed.php';
// Set the cache time for SimplePie
add_filter( 'wp_feed_cache_transient_lifetime', create_function( '$a', "return $cache_time;" ) );
// Build the SimplePie object
$rss = fetch_feed($feed);
// Check for errors in the RSS XML
if ( !is_wp_error( $rss ) ) {
// Set a limit for the number of items to parse
$maxitems = $rss->get_item_quantity($size);
$rss_items = $rss->get_items(0, $maxitems);
// Store the total number of items found in the feed
$i = 0;
$total_entries = count($rss_items);
// Output HTML
$html = "";
foreach ($rss_items as $item) {
$i++;
// Add a class of "last" to the last item in the list
if( $total_entries == $i ) {
$last = " class='last'";
} else {
$last = "";
}
// Store the data we need from the feed
$title = $item->get_title();
$link = $item->get_permalink();
$desc = $item->get_description();
$date_posted = $item->get_date('F j, Y');
// Output
$html .= "- ";
$html .= "
$title
";
if( $date == true ) $html .= "$date_posted";
$html .= "$desc";
$html .= " ";
}
$html .= "
";
} else {
$html = "An error occurred while parsing your RSS feed. Check that it's a valid XML file.";
}
return $html;
}
}
/** Define [rss] shortcode */
if( function_exists('base_rss_feed') && !function_exists('base_rss_shortcode') ) {
function base_rss_shortcode($atts) {
extract(shortcode_atts(array(
'size' => '10',
'feed' => 'https://wordpress.org/news/feed/',
'date' => false,
), $atts));
$content = base_rss_feed($size, $feed, $date);
return $content;
}
add_shortcode("rss", "base_rss_shortcode");
}Usage
Once you’ve added the functions to your functions.php file, you can use the following in your theme wherever you would like to output a list of RSS entries as an unordered list.
Parameters & Settings
$size— How many entries you want to parse and display. Default value is 5.$feed— The location of the RSS XML file. Default value is https://wordpress.org/news/feed/.$date— Display the date for each RSS entry. Default value is false.$cache_time— Optional. The number of seconds between each time WordPress checks for new items in the feed. Default is 1800, or 30 minutes.
As a Function in a Theme
if( function_exists('base_rss_feed') ) echo base_rss_feed(10, 'https://wordpress.org/news/feed/', true);As a Shortcode in the WYSIWYG Editor
[rss size="10" feed="https://wordpress.org/news/feed/" date="true"]The end result of this would look something like:
The HTML Output
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Give it some style!
/** RSS Feedlist */
.feedlist {
list-style:none;
padding:0;
margin:0 0 1.6em;
}
.feedlist li {
padding:0 0 10px;
border-bottom:1px solid #efefef;
margin:0 0 10px;
}
.feedlist li:last-child,
.feedlist li.last {
margin:0;
border:none;
padding:0;
}
.feedlist h3 {
margin:0;
}
.feedlist .date {
font-size:11px;
color:#999;
display:block;
}As a bonus, the last LI in the list has a class of last. I’ve found that this little bonus is handy for many CSS circumstances until we get full browser support for the :last-child selector.
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