RssHelper¶

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.

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 https://validator.w3.org/feed/.