RssHelper

class RssHelper(View $view, array $settings = array())

The RSS helper makes generating XML for RSS feeds easy.

Creating an RSS feed with the RssHelper

This example assumes you have a Posts Controller and Post Model already created and want to make an alternative view for RSS.

Creating an xml/rss version of posts/index is a snap with CakePHP. After a few simple steps you can simply append the desired extension .rss to posts/index making your URL posts/index.rss. Before we jump too far ahead trying to get our webservice up and running we need to do a few things. First parseExtensions needs to be activated, this is done in app/Config/routes.php:

Router::parseExtensions('rss');

In the call above we’ve activated the .rss extension. When using Router::parseExtensions() you can pass as many arguments or extensions as you want. This will activate each extension/content-type for use in your application. Now when the address posts/index.rss is requested you will get an xml version of your posts/index. However, first we need to edit the controller to add in the rss-specific code.

Controller Code

It is a good idea to add RequestHandler to your PostsController’s $components array. This will allow a lot of automagic to occur:

public $components = array('RequestHandler');

Our view will also use the TextHelper for formatting, so that should be added to the controller as well:

public $helpers = array('Text');

Before we can make an RSS version of our posts/index we need to get a few things in order. It may be tempting to put the channel metadata in the controller action and pass it to your view using the Controller::set() method but this is inappropriate. That information can also go in the view. That will come later though, for now if you have a different set of logic for the data used to make the RSS feed and the data for the HTML view you can use the RequestHandler::isRss() method, otherwise your controller can stay the same:

// Modify the Posts Controller action that corresponds to
// the action which deliver the rss feed, which is the
// index action in our example

public function index() {
    if ($this->RequestHandler->isRss() ) {
        $posts = $this->Post->find(
            'all',
            array('limit' => 20, 'order' => 'Post.created DESC')
        );
        return $this->set(compact('posts'));
    }

    // this is not an Rss request, so deliver
    // data used by website's interface
    $this->paginate['Post'] = array(
        'order' => 'Post.created DESC',
        'limit' => 10
    );

    $posts = $this->paginate();
    $this->set(compact('posts'));
}

With all the View variables set we need to create an rss layout.

Layout

An Rss layout is very simple, put the following contents in app/View/Layouts/rss/default.ctp:

if (!isset($documentData)) {
    $documentData = array();
}
if (!isset($channelData)) {
    $channelData = array();
}
if (!isset($channelData['title'])) {
    $channelData['title'] = $this->fetch('title');
}
$channel = $this->Rss->channel(array(), $channelData, $this->fetch('content'));
echo $this->Rss->document($documentData, $channel);

It doesn’t look like much but thanks to the power in the RssHelper it’s doing a lot of lifting for us. We haven’t set $documentData or $channelData in the controller, however in CakePHP your views can pass variables back to the layout. Which is where our $channelData array will come from setting all of the meta data for our feed.

Next up is view file for my posts/index. Much like the layout file we created, we need to create a View/Posts/rss/ directory and create a new index.ctp inside that folder. The contents of the file are below.

View

Our view, located at app/View/Posts/rss/index.ctp, begins by setting the $documentData and $channelData variables for the layout, these contain all the metadata for our RSS feed. This is done by using the View::set() method which is analogous to the Controller::set() method. Here though we are passing the channel’s metadata back to the layout:

$this->set('channelData', array(
    'title' => __("Most Recent Posts"),
    'link' => $this->Html->url('/', true),
    'description' => __("Most recent posts."),
    'language' => 'en-us'
));

The second part of the view generates the elements for the actual records of the feed. This is accomplished by looping through the data that has been passed to the view ($items) and using the RssHelper::item() method. The other method you can use, RssHelper::items() which takes a callback and an array of items for the feed. (The method I have seen used for the callback has always been called transformRss(). There is one downfall to this method, which is that you cannot use any of the other helper classes to prepare your data inside the callback method because the scope inside the method does not include anything that is not passed inside, thus not giving access to the TimeHelper or any other helper that you may need. The RssHelper::item() transforms the associative array into an element for each key value pair.

Note

You will need to modify the $postLink variable as appropriate to your application.

foreach ($posts as $post) {
    $postTime = strtotime($post['Post']['created']);

    $postLink = array(
        'controller' => 'posts',
        'action' => 'view',
        'year' => date('Y', $postTime),
        'month' => date('m', $postTime),
        'day' => date('d', $postTime),
        $post['Post']['slug']
    );

    // Remove & escape any HTML to make sure the feed content will validate.
    $bodyText = h(strip_tags($post['Post']['body']));
    $bodyText = $this->Text->truncate($bodyText, 400, array(
        'ending' => '...',
        'exact'  => true,
        'html'   => true,
    ));

    echo  $this->Rss->item(array(), array(
        'title' => $post['Post']['title'],
        'link' => $postLink,
        'guid' => array('url' => $postLink, 'isPermaLink' => 'true'),
        'description' => $bodyText,
        'pubDate' => $post['Post']['created']
    ));
}

You can see above that we can use the loop to prepare the data to be transformed into XML elements. It is important to filter out any non-plain text characters out of the description, especially if you are using a rich text editor for the body of your blog. In the code above we used strip_tags() and h() to remove/escape any XML special characters from the content, as they could cause validation errors. Once we have set up the data for the feed, we can then use the RssHelper::item() method to create the XML in RSS format. Once you have all this setup, you can test your RSS feed by going to your site /posts/index.rss and you will see your new feed. It is always important that you validate your RSS feed before making it live. This can be done by visiting sites that validate the XML such as Feed Validator or the w3c site at http://validator.w3.org/feed/.

Note

You may need to set the value of ‘debug’ in your core configuration to 1 or to 0 to get a valid feed, because of the various debug information added automagically under higher debug settings that break XML syntax or feed validation rules.

Rss Helper API

property RssHelper::$action

Current action

property RssHelper::$base

Base URL

property RssHelper::$data

POSTed model data

property RssHelper::$field

Name of the current field

property RssHelper::$helpers

Helpers used by the RSS Helper

property RssHelper::$here

URL to current action

property RssHelper::$model

Name of current model

property RssHelper::$params

Parameter array

property RssHelper::$version

Default spec version of generated RSS.

RssHelper::channel(array $attrib = array (), array $elements = array (), mixed $content = null)
Return type:string

Returns an RSS <channel /> element.

RssHelper::document(array $attrib = array (), string $content = null)
Return type:string

Returns an RSS document wrapped in <rss /> tags.

RssHelper::elem(string $name, array $attrib = array (), mixed $content = null, boolean $endTag = true)
Return type:string

Generates an XML element.

RssHelper::item(array $att = array (), array $elements = array ())
Return type:string

Converts an array into an <item /> element and its contents.

RssHelper::items(array $items, mixed $callback = null)
Return type:string

Transforms an array of data using an optional callback, and maps it to a set of <item /> tags.

RssHelper::time(mixed $time)
Return type:string

Converts a time in any format to an RSS time. See TimeHelper::toRSS().