mlanthaler: Added support for conditional GETs for RSS feeds (added support for ETag an Last-Modified headers).

(merged from branches/gsoc)


git-svn-id: svn://svn.silverstripe.com/silverstripe/open/modules/sapphire/trunk@42105 467b73ca-7a2a-4603-9d3b-597d59a354a9

api/RSSFeed.php

@@ -1,11 +1,99 @@
 <?php
 
+/**
+ * RSSFeed class
+ *
+ * This class is used to create an RSS feed.
+ */
 class RSSFeed extends ViewableData {
-	protected $entries;
-	protected $title, $description, $link;
-	protected $titleField, $descriptionField, $authorField;
 
-	function __construct(DataObjectSet $entries, $link, $title, $description = null, $titleField = "Title", $descriptionField = "Content", $authorField = null) {
+	/**
+	 * Holds the feed entries
+	 *
+	 * @var DataObjectSet
+	 */
+	protected $entries;
+
+	/**
+	 * Title of the feed
+	 *
+	 * @var string
+	 */
+	protected $title;
+
+	/**
+	 * Description of the feed
+	 *
+	 * @var string
+	 */
+	protected $description;
+
+	/**
+	 * Link to the feed
+	 *
+	 * @var string
+	 */
+	protected $link;
+
+	/**
+	 * Name of the title field of feed entries
+	 *
+	 * @var string
+	 */
+	protected $titleField;
+
+	/**
+	 * Name of the description field of feed entries
+	 *
+	 * @var string
+	 */
+	protected $descriptionField;
+
+	/**
+	 Name of the author field of feed entries
+	 *
+	 * @var string
+	 */
+	protected $authorField;
+
+	/**
+	 * Last modification of the RSS feed
+	 *
+	 * @var int Unix timestamp of the last modification
+	 */
+	protected $lastModified;
+
+	/**
+	 * ETag for the RSS feed (used for client-site caching)
+	 *
+	 * @var string The value for the HTTP ETag header.
+	 */
+	protected $etag;
+
+
+	/**
+	 * Constructor
+	 *
+	 * @param DataObjectSet $entries RSS feed entries
+	 * @param string $link Link to the feed
+	 * @param string $title Title of the feed
+	 * @param string $description Description of the field
+	 * @param string $titleField Name of the field that should be used for the
+	 *                           titles for the feed entries
+	 * @param string $descriptionField Name of the field that should be used
+	 *                                 for the description for the feed
+	 *                                 entries
+	 * @param string $authorField Name of the field that should be used for
+	 *                            the author for the feed entries
+	 * @param int $lastModified Unix timestamp of the latest modification
+	 *                          (latest posting)
+	 * @param string $etag The ETag is an unique identifier that is changed
+	 *                         every time the representation does
+	 */
+	function __construct(DataObjectSet $entries, $link, $title,
+											 $description = null, $titleField = "Title",
+											 $descriptionField = "Content", $authorField = null,
+											 $lastModified = null, $etag = null) {
 		$this->entries = $entries;
 		$this->link = $link;
 		$this->description = $description;
@@ -14,13 +102,31 @@ class RSSFeed extends ViewableData {
 		$this->titleField = $titleField;
 		$this->descriptionField = $descriptionField;
 		$this->authorField = $authorField;
+
+		$this->lastModified = $lastModified;
+		$this->etag = $etag;
 	}
 
+
+	/**
+	 * Include an link to the feed
+	 *
+	 * @param string $url URL of the feed
+	 * @param string $title Title to show
+	 */
 	static function linkToFeed($url, $title = null) {
 		$title = Convert::raw2xml($title);
-		Requirements::insertHeadTags("<link rel=\"alternate\" type=\"application/rss+xml\" title=\"$title\" href=\"$url\" />");
+		Requirements::insertHeadTags(
+			'<link rel="alternate" type="application/rss+xml" title="' . $title .
+			'" href="' . $url . '" />');
 	}
 
+
+	/**
+	 * Get the RSS feed entries
+	 *
+	 * @return DataObjectSet Returns the {@link RSSFeed_Entry} objects.
+	 */
 	function Entries() {
 		$output = new DataObjectSet();
 		foreach($this->entries as $entry) {
@@ -29,52 +135,150 @@ class RSSFeed extends ViewableData {
 		return $output;
 	}
 
+
+	/**
+	 * Get the title of thisfeed
+	 *
+	 * @return string Returns the title of the feed.
+	 */
 	function Title() {
-		return $this->title;
+		return Convert::raw2xml($this->title);
 	}
+
+
+	/**
+	 * Get the URL of this feed
+	 *
+	 * @return string Returns the URL of the feed.
+	 */
 	function Link() {
 		return Director::absoluteURL($this->link);
 	}
+
+
+	/**
+	 * Get the description of this feed
+	 *
+	 * @return string Returns the description of the feed.
+	 */
 	function Description() {
-		return $this->description;
+		return Convert::raw2xml($this->description);
 	}
 
+
+	/**
+	 * Output the feed to the browser
+	 */
 	function outputToBrowser() {
+		if(is_int($this->lastModified)) {
+			HTTP::register_modification_timestamp($this->lastModified);
+			header('Last-Modified: ' . gmdate("D, d M Y H:i:s", $this->lastModified) . ' GMT');
+		}
+		if(!empty($this->etag)) {
+			HTTP::register_etag($this->etag);
+		}
+
+		$body = str_replace('&nbsp;', '&#160;', $this->renderWith('RSSFeed'));
+		HTTP::add_cache_headers($body);
 		header("Content-type: text/xml");
-		echo str_replace('&nbsp;', '&#160;', $this->renderWith('RSSFeed'));
+		echo $body;
+	}
 }
 
-}
 
+
+/**
+ * RSSFeed_Entry class
+ *
+ * This class is used for entries of an RSS feed.
+ *
+ * @see RSSFeed
+ */
 class RSSFeed_Entry extends ViewableData {
-	protected $titleField, $descriptionField, $authorField;
+
+	/**
+	 * The object that represents the item, it contains all the data.
+	 *
+	 * @var mixed
+	 */
+	protected $failover;
+
+	/**
+	 * Name of the title field of feed entries
+	 *
+	 * @var string
+	 */
+	protected $titleField;
+
+	/**
+	 * Name of the description field of feed entries
+	 *
+	 * @var string
+	 */
+	protected $descriptionField;
+
+	/**
+	 Name of the author field of feed entries
+	 *
+	 * @var string
+	 */
+	protected $authorField;
+
 
 	/**
 	 * Create a new RSSFeed entry.
 	 */
-	function __construct($entry, $titleField, $descriptionField, $authorField) {
+	function __construct($entry, $titleField, $descriptionField,
+											 $authorField) {
 		$this->failover = $entry;
 		$this->titleField = $titleField;
 		$this->descriptionField = $descriptionField;
 		$this->authorField = $authorField;
 	}
 
+
+	/**
+	 * Get the description of this entry
+	 *
+	 * @return string Returns the description of the entry.
+	 */
 	function Title() {
 		if($this->titleField)
 			return $this->failover->obj($this->titleField);
 	}
+
+
+	/**
+	 * Get the description of this entry
+	 *
+	 * @return string Returns the description of the entry.
+	 */
 	function Description() {
 		if($this->descriptionField)
 			return $this->failover->obj($this->descriptionField);
 	}
+
+
+	/**
+	 * Get the author of this entry
+	 *
+	 * @return string Returns the author of the entry.
+	 */
 	function Author() {
 		if($this->authorField)
 			return $this->failover->obj($this->authorField);
 	}
 
+
+	/**
+	 * Get a link to this entry
+	 *
+	 * @return string Returns the URL of this entry
+	 */
 	function AbsoluteLink() {
 		return $this->failover->AbsoluteLink();
 	}
 }
 
+
 ?>