Well don’t worry I am busy to create that and it is almost finished. In the mean while, I wanted to share some stuff I learned while creating this RSS feed.

The Beginning

The first thing we need is a function that actually creates the RSS feed. This function doesn’t need any parameters and it also shouldn’t return anything.

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<?php
function myGreatPluginRSSFeed() {
    // Function content goes here.

}
?>

This function must create the whole feed form the beginning to the end. So, you also have to include the xml/rss header. I ripped something from the default WordPress feed that should work for any blog.

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<rss version="2.0"
	xmlns:content="http://purl.org/rss/1.0/modules/content/"
	xmlns:dc="http://purl.org/dc/elements/1.1/"
	xmlns:atom="http://www.w3.org/2005/Atom"
	xmlns:sy="http://purl.org/rss/1.0/modules/syndication/">

	<channel>
		<title><?php bloginfo_rss('name'); wp_title_rss(); ?></title>
		<link><?php bloginfo_rss('url') ?></link>
		<atom:link href="<?php self_link(); ?>" rel="self" type="application/rss+xml" />
		<description><?php bloginfo_rss("description") ?></description>
		<language><?php echo get_option('rss_language'); ?></language>
		<sy:updatePeriod><?php echo apply_filters( 'rss_update_period', 'hourly' ); ?></sy:updatePeriod>
		<sy:updateFrequency><?php echo apply_filters( 'rss_update_frequency', '1' ); ?></sy:updateFrequency>

		<item>
		</item>

	</channel>
</rss>

Now, you could see the <item> and </item> tags, that is where we are going to add our feed items. From this moment I assume that all our RSS data is located in an array like this one.

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$rssItems = array(
	'item_1'=>array(
		'Title',
		'Link',
		'Author',
		'Date',
		'Description',
		'Content'
		),
	'item_2'=>array(
		'Title',
		'Link',
		'Author',
		'Date',
		'Description',
		'Content'
		)
	);

And so on. For adding the items to our feed, we simply use a foreach loop.

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foreach ($rssItems as $item) {
	echo '<item>';
	echo '<title>' . $item['Title'] . '</title>';
	echo '<link>' . $item['Link'] . '</link>';
	echo '<dc:creator>' . $item['Author'] . '</dc:creator>';
	echo '<pubDate>' . mysql2date('D, d M Y H:i:s +0000', $item['Date']) . '</pubDate>';
	echo '<description>' . $item['Description'] . '</description>';
	echo '<content:encoded><![CDATA[' . $item['Content'] . ']]></content:encoded>';
	echo '</item>';
}

The mysql2date function is a WordPress function that converts our date to the format we want for our feed. The input should be the date in the following format: d-m-Y H:i:s. See php.net for more information about the date formatting.

Now we have finished our function, we have only one thing to do.

Adding the RSS Feed to WordPress

To add the feed, we could use one simple function, build-in in WordPress since version 2.1.0. This is the add_feed function. This function has two parameters.

• $feedname; The name of your feed.
• $function; The function that creates the feed. (The one we created above)

So lets say we name our feed: ‘guestbook’, then we should call the add_feed function this way:

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<?php
// Add our new RSS feed.

add_feed('guestbook', 'myGreatPluginRSSFeed');
?>

Now our feed is added and working! One thing you might be asking yourself is: Where could I find my feed? Well, that’s simple.
If you are using permalinks on your blog (could be checked this way: $wp_rewrite->using_permalinks()), then your feed is located at: http://your.website.com/[feedname].
If you don’t use permalinks, your feed is located at: http://your.website.com/?feed=[feedname].

Done!

After all our hard work, we have created one beautiful RSS 2.0 feed, working with WordPress. Any questions? Please leave a comment.

I searched the whole source code of this great piece of blogging software, and not on one single line I found even one session. Also the session_start() function is not called, but I still needed my sessions to work .

So I started searching Google for a fix of my problem. I found a lot of people asking the same question: “Why do sessions not work in WordPress?” Finally I found a solution to fix this little issue and guess what, it is a simple one.

The Solution

The only thing you have to do is call session_start(); before any output is send to the client. Now you might think: Nice, but what happens when I upgrade my WordPress installation to the latest version? Well, yes, your changes will be lost. That is the reason why we first should think of where to add these changes..

Normally upgrading your installation will replace all files, except one. Yes, it is the wp-config.php file. And even better, there isn’t send any output to a client yet, when this file is loaded.

So, we add the next lines of code to our wp-config.php file:

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/**
 *  Enable sessions
 */
if (!session_id())
    session_start();

And sessions are enabled on your blog!
I think the best place to add these lines is at the top of the config file, so immediately after the php starting tag (<?php).

I hope this will help you out when facing the same problem.

As you could have read here, the current release of my code highlighter has some trouble with highlighting PHP on servers running PHP version 4. I told you I should try to fix the problem and include a better PHP highlighter in the next release.

I worked very hard this morning to get PHP fixed, and I’m proud to announce that PHP is almost working the way it should. That means: including servers running PHP4.

You want an example? Sure, here it is:

PHP Code Like It Should

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<?php
mysql_connect ($host, $user, $password);
$result = mysql_db_query ('Database', 'select * from table');
while ($row = mysql_fetch_assoc ($result))
{
	echo $row['user_id'];
	echo $row['fullname'];
}
mysql_free_result ($result);
?>

So, What’s Next?

After this highlighter is finished, I create one for JavaScript and properly one for Java. As soon as they all work the way it should, I will release version 1.1.

See you.

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$var = [condition] ? [true] : [false];

1. Condition = The condition which must be met.
2. True = Executed if the condition is met.
3. False = Executed if the condition failes.

Thus, the above statement means the same as this enlarged structure:

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<?php
if (condition) {
    $var = [true];
} else {
    $var = [false];
}
?>

Examples

Let’s take a look at some example.

Filled in a name?

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<?php
$name = isset($_POST['name'])?$_POST['name']:'Unknown';
// If $_POST['name'] exists, we use that for the name, else we use Unknown.

?>

We can also use it to easily echo stuff:

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<?php
$fruit = 'apple';
echo ('pear' == $fruit)?'pear':'apple';
// Will echo apple

?>

It is even possible to use php-functions inside it:

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<?php
$input = 'Just a string to be hashed';
$hashMethod = 'sha1';
$hash = ('sha1' == $hashMethod)?sha1($input):md5($input);
// $hash will contain an sha1 hash of $input

?>

Conclusion

The short if-else structure is a good way to keep your code organized. However, it is not possible to use such a thing as: ‘elseif’.
I use it all the time to assign values to variables, with just one rule of code, I’m sure my vars have a proper value. Especially when using forms, this is a very useful function of PHP.