How to do item paging

Although this tutorial doesn't require SimplePie (this is just plain ol' PHP), there have been a few users who have asked for this. In this tutorial we will merge multiple feeds together, and allow for a variety of paging options (5, 10, or 20 items per page; Previous and Next buttons).

Compatibility

Supported in SimplePie 1.0.
Code in this tutorial should be compatible with PHP 4.3 or newer, and should not use PHP short tags, in order to support the largest number of PHP installations.

Code source

<?php
require_once('simplepie.inc');
 
// Set your own configuration options as you see fit.
$feed = new SimplePie();
$feed->set_feed_url(array(
	'http://www.newsvine.com/_feeds/rss2/tag?id=technology',
	'http://uneasysilence.com/feed/',
	'http://www.tuaw.com/rss.xml'
));
$success = $feed->init();
 
// Make sure the page is being served with the right headers.
$feed->handle_content_type();
 
// Set our paging values
$start = (isset($_GET['start']) && !empty($_GET['start'])) ? $_GET['start'] : 0; // Where do we start?
$length = (isset($_GET['length']) && !empty($_GET['length'])) ? $_GET['length'] : 5; // How many per page?
$max = $feed->get_item_quantity(); // Where do we end?
 
// When we end our PHP block, we want to make sure our DOCTYPE is on the top line to make 
// sure that the browser snaps into Standards Mode.
?><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en-US" lang="en-US">
<head>
<title>SimplePie: Demo</title>
 
<link rel="stylesheet" href="styles.css" type="text/css" media="screen, projector" />
 
</head>
 
<body>
<div id="site">
	<?php
	// If we have an error, display it.
	if ($feed->error())
	{
		echo '<div class="sp_errors">' . "\r\n";
		echo '<p>' . htmlspecialchars($feed->error()) . "</p>\r\n";
		echo '</div>' . "\r\n";
	}
	?>
 
	<?php if ($success): ?>
		<?php
		// get_items() will accept values from above.
		foreach($feed->get_items($start, $length) as $item):
			$feed = $item->get_feed();
		?>
 
			<div class="chunk">
 
				<h4><?php if ($item->get_permalink()) echo '<a href="' . $item->get_permalink() . '">'; echo $item->get_title(true); if ($item->get_permalink()) echo '</a>'; ?></h4>
				<?php echo $item->get_content(); ?>
				<p class="footnote">Source: <a href="<?php echo $feed->get_permalink(); ?>"><?php echo $feed->get_title(); ?></a> | <?php echo $item->get_date('j M Y, g:i a'); ?></p>
 
			</div>
 
		<?php endforeach; ?>
	<?php endif; ?>
 
	<?php
	// Let's do our paging controls
	$next = (int) $start + (int) $length;
	$prev = (int) $start - (int) $length;
 
	// Create the NEXT link
	$nextlink = '<a href="?start=' . $next . '&length=' . $length . '">Next &raquo;</a>';
	if ($next > $max)
	{
		$nextlink = 'Next &raquo;';
	}
 
	// Create the PREVIOUS link
	$prevlink = '<a href="?start=' . $prev . '&length=' . $length . '">&laquo; Previous</a>';
	if ($prev < 0 && (int) $start > 0)
	{
		$prevlink = '<a href="?start=0&length=' . $length . '">&laquo; Previous</a>';
	}
	else if ($prev < 0)
	{
		$prevlink = '&laquo; Previous';
	}
 
	// Normalize the numbering for humans
	$begin = (int) $start + 1;
	$end = ($next > $max) ? $max : $next;
	?>
 
	<p>Showing <?php echo $begin; ?>&ndash;<?php echo $end; ?> out of <?php echo $max; ?> | <?php echo $prevlink; ?> | <?php echo $nextlink; ?> | <a href="<?php echo '?start=' . $start . '&length=5'; ?>">5</a>, <a href="<?php echo '?start=' . $start . '&length=10'; ?>">10</a>, or <a href="<?php echo '?start=' . $start . '&length=20'; ?>">20</a> at a time.</p>
</div>
 
</body>
</html>

tutorial/how_to_do_item_paging.txt · Last modified: 2011/03/06 03:56 (external edit)