====== HowTo create RSS feed using Limb2 ======


RSS is an essential part of every site with rich content. We'd like to show how easy it is to create a RSS feed with Limb and WACT.

Say, we'd like to have the RSS feed of the latest news objects and documents.

Let's create a simple **last-news-feed.php** script, it's going to accomplish the following tasks:
  * fetching of news and documents objects
  * merge fetched objects and sort them by last modified date, if date is equal(very rare), then additionally sort by node id(since they are incremental)
  * normalize hrefs in order to make them absolute, href='/root/test/../new' should become href='http://yourdomain.com/root/new'
  * pass the processed dataset into WACT template

We think the following code should be self explanatory:

<code php>
<?php
require_once('setup.php');
require_once(LIMB_DIR . '/core/template/template.class.php');
require_once(LIMB_DIR . '/core/fetcher.class.php');
require_once(LIMB_DIR . '/core/lib/http/uri.class.php');
require_once(LIMB_DIR . '/core/lib/util/array_dataset.class.php');
require_once(LIMB_DIR . '/core/lib/system/sys.class.php');

define('CONTENT_LOCALE_ID', DEFAULT_CONTENT_LOCALE_ID);

//sorting callback used in uasort
function sorter($a, $b)
{
  $date1 = $a['modified_date'];
  $date2 = $b['modified_date'];

  if ($date1 == $date2)
  {
    if($a['node_id'] > $b['node_id'])
      return -1;
    else
      return 1;
  }

  return ($date1 > $date2) ? -1 : 1;
}

//function that normalizes hrefs in $content using $base_path to resolve relative links
function fix_hrefs($base_path, $content)
{
  $GLOBALS['base_path'] = $base_path;
  return preg_replace_callback('~href=(&quot;|\')?([^&quot;\'>\s]+)(&quot;|\')?~', '_replace_callback', $content);
}

//preg_replace_callback function, does the dirty job of regular expression replacing
function _replace_callback($matches)
{
  if(preg_match('~(https?|ftp)://~', $matches[2]))
    return $matches[0];

  $url = get_qualified_url($GLOBALS['base_path'], $matches[2]);

  return &quot;href='{$url}'&quot;;
}

//small helper function that actually normalizes the href
function get_qualified_url($base_path, $raw_path)
{
  $path = $raw_path;

  if($path{0} != '/')
    $path = uri :: resolve_path($base_path . '/' . $path);

  return 'http://' . sys :: hostname() . $path;
}

$counter = 0;
$params = array(
  'limit' => 3,
  'order' => array('modified_date' => 'DESC')
);

$arr_news = fetch('news_object', $counter, $params, 'fetch_accessible');

$params = array(
  'limit' => 3,
  'order' => array('modified_date' => 'DESC')
);
$arr_documents = fetch('document', $counter, $params, 'fetch_accessible');

$arr = array_merge($arr_documents, $arr_news);

uasort($arr, 'sorter');

foreach($arr as $key => $data)
{
  $arr[$key]['annotation'] = fix_hrefs($data['path'], $data['annotation']);
  $arr[$key]['path'] = get_qualified_url($data['path'], $data['path']);
}

$ds = new array_dataset($arr);

$template = new template('/rss/last_news.rss');
$template->set('xml', '<!--l version="1.0" encoding="utf-8-->');

$news =&amp; $template->find_child('last_news');
$news->register_dataset($ds);

header(&quot;Content-Type: application/xml&quot;);
$template->display();

?>
</code>

And here goes the template itself:

<code xml>
{$xml}
<!DOCTYPE rss [<!ENTITY % HTMLlat1 PUBLIC &quot;-//W3C//ENTITIES Latin 1 for XHTML//EN&quot; &quot;http://www.w3.org/TR/xhtml1/DTD/xhtml-lat1.ent&quot;>]>
<rss version=&quot;0.92&quot; xml:base=&quot;http://limb-project.com&quot;>

<channel>
 <title>YourDomain.com last news</title>
 <link>http://YourDomain.com</link>
 <description>YourDomain.com site</description>
 <language>en</language>

<grid:LIST id='last_news'>
 <grid:ITERATOR>

  <item>
   <title>{$title}</title>
   <link>{$path}</link>
   <description>
      <core:HTMLSPECIALCHARS hash_id='annotation'>
   </description>
   <pubDate>
    <locale:DATE_FORMAT hash_id='modified_date' locale_format='short_date_time' type='stamp'>
   </pubDate>
  </item>

  </grid:ITERATOR>
</grid:LIST>

</channel>
</rss>
</code>

Note that we use **<core:HTMLSPECIALCHARS>** tag in order to sanitize the html content and we use **<locale:DATE_FORMAT>** tag to display properly formatted date.

Now place the script to **PROJECT_DIR/last-news-feed.php** and template to **PROJECT_DIR/design/main/templates/rss/last_news.rss**. Make a neat link to your RSS feed somewhere in the layout, sort like

<code xml>
<a href='/last-news-feed.php'><img src='/design/main/images/xml.gif'>]]
</code>

and...that really should be it!