SimpleXML + Solar’s Alternate Formats = Easy RSS

Creating your own RSS feeds is generally straightforward, but it’s even easier when you combine PHP’s SimpleXML and Solar’s alternate format mechanism.

If you are new to Solar, you better check out the manual.

Setup Solar

Solar makes it easy to specify an alternate format simply by changing the extension of your request. For example, say you have a list of articles at

http://www.example.com/articles/browse

Here, “articles” refers to the controller, and “browse” refers to the action. By default, no format was explicitly specified, so the default text/html is used when outputting the content to the browser. If you wanted to use an alternate format, you can specify the format by using an extension. Here are a couple of examples:

  • http://www.example.com/articles/browse.rdf (application/rdf+xml)
  • http://www.example.com/articles/browse.xml (application/xml)

Before these will actually work, you have to perform a couple of tasks in your Solar environment.

First, you need to tell Solar that a given format (or formats) are allowed for a given action. Do this by adding code to the top of the Articles.php application controller.

<?php 
protected function _setup()
{
    // chain to parent
    parent::_setup();
 
    // allow xml and rdf formats for the browse action
    $this->_action_format = array(
        'browse'=>array('xml', 'rdf')
    );
}
?>

Second, you need to create an appropriate view for each format specified. In the example above, you need two new views. One for the xml format, and one for the rdf format. The naming convention for each view is as follows:

  • browse.xml.php
  • browse.rdf.php

Now, when browsing to http://www.example.com/articles/browse.xml, Solar will use the browse.xml.php view and output accordingly.

Create Markup with SimpleXML

Before using SimpleXML to format the xml output, it’s assumed that we have a collection of article records to work with, and that they are available to the view as $this->list.

Inside the browse.xml.php file…

<?php
 
// Get the current URI
$uri = Solar::factory('Solar_Uri_Action');
$uri->format = null; // reset the format
$link = $uri->get(true); // get the full uri, including http:// etc
 
$xml = new SimpleXMLElement('<rss version="2.0"></rss>');
$channel = $xml->addChild('channel');
$channel->addChild('title', 'My RSS Feed');
$channel->addChild('link', $link);
$channel->addChild('description', 'My RSS feed about something of interest');
$channel->addChild('language', 'en-ca');
$channel->addChild('pubDate', $this->list[0]->date_added); // assume the list in chronologically ordered
$channel->addChild('lastBuildDate', $this->list[0]->date_added.' MST');
$channel->addChild('webMaster', 'me@example.com');
foreach ($this->list as $item) {
	$uri->path = 'articles/read/' . $item->getPrimaryVal(); // set up the path to each article
	$title = $channel->addChild('item');
	$title->addChild('title', $this->escape($item->title));
	$title->addChild('link', $this->escape($uri->get(true)));
	$title->addChild('description', $this->escape($item->description));
	$title->addChild('pubDate', $this->date($item->date_added, "D, d M Y")); // Solar's date() view helper
}
echo $xml->asXML();
?>

And that’s basically all there is to it! Browse to http://www.example.com/articles/browse.xml and you should see an xml version of the page.

References

This entry was posted on Thursday, February 17th, 2011 at 4:26 pm and is filed under PHP, Solar. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.

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