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RSSParser
World Wide Web Server edited this page Jul 4, 2012
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I have created this page to document the RSSParser library I have put together. I wanted to add RSS items and couldn't find anything to achieve this and so have put this together for anyone else that would like it.
The RSS parsing was adapted closely from [url=http://www.techbytes.co.in/blogs/2006/01/15/consuming-rss-with-php-the-sim ple-way/]this[/url] link.
Because the class is loading an externally hosted file performance van very wildly so I have added some simple caching into the class.
The class is only on its first revision so there may well be bugs within it, if you find any please let me know and I will be happy to look into them.
If anyone has any suggestions or comments I'd be happy to hear them
Cheers
/Matt
[h3]Instructions[/h3] In order to make use of this library simply copy and paste this class into a php file called RSSParser.php and save it into your libraries file (system/application/libraries/). You can then load this library as you would any other library within your application.
[h3]Example Usage[/h3] The below code demonstrates how you would use the RSSParser class
[code] //Load the shiny new rssparse $this->load->library('RSSParser', array('url' => 'http://link.to/rss.xml', 'life' => 2)); //Get six items from the feed $data = $this->rssparser->getFeed(6); [/code]
The constructor expects the url of the rss feed, and the lifetime of the cache file in minutes. The getFeed function expects the number of feed items you would like to retrieve.
[h3]RSSParser class[/h3]
[code] <php if (!defined('BASEPATH')) exit('No direct script access allowed');
/*
- This class is written based entirely on the work found below
- www.techbytes.co.in/blogs/2006/01/15/consuming-rss-with-php-the-simple-way/
- All credit should be given to the original author */
class RSSParser { // ===================// //Instance vars // // ===================//
/* Feed URI */
var $feed_uri;
/* The idea is to push and pop tag names onto a stack depending upon whether */
/* we encounter an open tag or a close tag respectively */
var $tag_stack;
/* We are parsing items one at a time, and at any time, this array will
contain elements for the current item being parsed.
Just prior to parsing the next item in the RSS, the data in this array
is emptied and pushed on to the $data associative array defined below
and the process is repeated till there are no further items in the RSS file */
var $current_feed;
/* Store character data between the current open and close tags being parsed */
var $character_data;
/* Associative array containing all the feed items */
var $data;
/* Store RSS Channel Data in an array */
var $channel_data;
/* Boolean variable which indicates whether an RSS feed was unavailable */
var $feed_unavailable;
/* Cache lifetime */
var $cache_life;
/* Flag to write to cache - defaulted to false*/
var $write_cache_flag = false;
/* Code Ignitor cache directory */
var $cache_dir;
// ================ //
// Constructor //
// ================ //
function RSSParser($params) {
$this->CI = &get_instance();
$dir = $this->CI->config->item('cache_path');
$this->cache_dir = ($dir == '') ? BASEPATH.'cache/' : $dir;
//$this->cache_dir = '/system/cache';
$this->cache_life = $params['life'];
$this->feed_uri = $params['url'];
$this->tag_stack = array();
$this->character_data = '';
$this->current_feed["title"] = '';
$this->current_feed["description"] = '';
$this->current_feed["link"] = '';
$this->data = array();
$this->channel_data = array();
//Attempt to parse the feed
$this->parse();
}
// =============== //
// Methods //
// =============== //
function parse() {
//Are we caching?
if ($this->cache_life != 0)
{
$filename = $this->cache_dir.'rss_Parse_'.md5($this->feed_uri);
//is there a cache file ?
if (file_exists($filename))
{
//Has it expired?
$timedif = (time() - filemtime($filename));
if ($timedif < ( $this->cache_life * 60))
{
//its ok - so we can skip all the parsing and just return the cached array here
$this->data = unserialize(implode('', file($filename)));
return true;
}
//So raise the falg
$this->write_cache_flag = true;
} else {
//Raise the flag to write the cache
$this->write_cache_flag = true;
}
}
/* instantiate the in-built parser */
$parser =& xml_parser_create();
/* Bind this class object to the parser. This tells the parser to call
this very class object's methods, such as event handlers, instead of
any global functions. This is because in this example we make the event
handler methods a part of this very class.Alternatively, what we could
have done was create a separate class for these event handlers, in
which case, instead of passing $this to xml_set_object(), we would have
passed that other class's object instance variable */
xml_set_object(&$parser, $this);
/* Next we configure the parser to not automatically convert all tag names to uppercase. */
xml_parser_set_option(&$parser, XML_OPTION_CASE_FOLDING, false);
/* Okay, now we inform the parser as to which functions will be
responsible for handling events trigerred by open and close xml tags.
Note that further down, we will be implementing these functions */
xml_set_element_handler(&$parser, 'handleOpenTag', 'handleCloseTag');
/* Finally, we register the callback function for handling events
whenever character data is encountered by the parser */
xml_set_character_data_handler(&$parser, 'handleCharacterData');
/* lets try opening the rss feed file <85> this file can be a local
one or can be in a remote location specified by a URI */
if(!($fp = @fopen($this->feed_uri, 'r'))) {
xml_parser_free(&$parser);
$this->feed_unavailable = true;
return false;
}
/* Let's start reading the file 4096 characters at a time */
while($line = fread($fp, 4096)) {
/* We now invoke the in-built Expat parser, and pass it the parser
object that we created, and the data that we've read so far. Note
that once control is passed to the Expat parser, it will
automatically invoke callback functions that we registered above
whenever events are triggered. Shortly, we will implement these
callback functions */
xml_parse(&$parser, $line, feof($fp));
}
/* All done. Time to free up all the resources. */
fclose($fp);
xml_parser_free(&$parser);
//Do we need to write the cache file?
if ($this->write_cache_flag)
{
if ( ! $fp = @fopen($filename, 'wb'))
{
echo "ERROR";
log_message('error', "Unable to write ache file: ".$cache_path);
return;
}
flock($fp, LOCK_EX);
fwrite($fp, serialize($this->data));
flock($fp, LOCK_UN);
fclose($fp);
}
return true;
}
/* The open tag event handler */
function handleOpenTag($parser, $tag_name, $tag_attributes) {
switch($tag_name) {
/* Most RSS feed formats make use of the <rss> tag to specify
that we're looking at an RSS file. Some formats, like RSS 1.0, make use
of <rdf :RDF> tag so we merge both the above case and this one, and
treat them as the same thing. */
case 'rss':
case 'rdf:RDF':
/* Push it onto the stack. Later we'll pop it off, when we encounter
the close tag version */
array_push($this->tag_stack, $tag_name);
break;
case 'item':
case 'title':
case 'description':
case 'link':
case 'pubDate':
/* before pushing these onto the stack just check if the rss or the
rdf:RDF tags are in the stack. We dont need to check this actually
<85>.. this is just to prevent wrongly formed feeds from messing up
our code */
if(in_array('rss', $this->tag_stack) || in_array('rdf:RDF', $this->tag_stack))
array_push($this->tag_stack, $tag_name);
break;
default:
}
}
/* The character data handler function */
function handleCharacterData($parser, $cdata) {
if(in_array('rss', $this->tag_stack) || in_array('rdf:RDF', $this->tag_stack)) {
$stack_top_index = count($this->tag_stack) - 1;
/* if the last tag that was pushed onto the stack is either one of
title, description or link, then let's store the character data. This
character data is recorded in the class variable $character_data. Note
carefully the .= assignment below. It could easily have been simply an
= assignment. But, very often multiple events are triggered for the
same data in between an open and a close tag. so we "join" all this
data together and store it in the variable $character_data */
if(in_array($this->tag_stack[$stack_top_index], array('title', 'description', 'link', 'pubDate')))
$this->character_data .= $cdata;
}
}
/* The close tag handler function */
function handleCloseTag($parser, $tag_name) {
switch($tag_name) {
case 'rss':
case 'rdf:RDF':
array_pop($this->tag_stack);
break;
case 'title':
case 'description':
case 'link':
case 'pubDate';
/* There are two possible locations where the <title>,
<description> and <link> can be found: either nested inside
item tags, or outside it. Depending upon this, they either
correspond to individual feed items or channel data for the
entire feed itself. This is what we check now. Also note below
that the $character_data class variable holds data in between
open and close tags corresponding to the element that has just
triggered this handler function. */
if(in_array('item', $this->tag_stack)) {
$this->current_feed["$tag_name"] = $this->character_data;
} else {
$this->channel_data["$tag_name"] = $this->character_data;
}
array_pop($this->tag_stack);
$this->character_data = '';
break;
case 'item':
/* Okay, we know that the item tags encapsulates the title,
description and the link tags. so it's pretty obvious that when
you encounter </item> all data for the current item has
already been fetched and placed in the $current_feed class
variable. So, we now take this data for the current feed and
push it onto the $data array variable and then re-initialize the
$current_feed variable in preparation for the next feed item.
The $data class variable will, in the end, store all the feed
items in an array format */
array_pop($this->tag_stack);
array_push($this->data, $this->current_feed);
$this->current_feed = array();
break;
default:
}
}
/* Return the feeds one at a time: when there are no more feeds return false
* @param No of items to return from the feed
* @return Associative array of items
*/
function getFeed($num) {
$c = 0;
$return = array();
foreach($this->data AS $item)
{
$return[] = $item;
$c++;
if($c == $num) break;
}
return $return;
}
/* Return channel data for the feed */
function & getChannelData() {
$flag = false;
if(!empty($this->channel_data)) {
return $this->channel_data;
} else {
return $flag;
}
}
/* Were we unable to retreive the feeds ? */
function errorInResponse() {
return $this->feed_unavailable;
}
} ?> [/code]