Home arrow PHP arrow Page 6 - Plugging RDF Content Into Your Web Site With PHP

Nesting Time - PHP

A Web site which dynamically updates itself with the latestnews and information? Nope, it's not as far-fetched as it sounds. Asthis article demonstrates, all you need is a little imagination, acouple of free RDF files and some PHP glue.

TABLE OF CONTENTS:
  1. Plugging RDF Content Into Your Web Site With PHP
  2. Have Content, Will Syndicate
  3. Switching Channels
  4. Fresh Meat
  5. Capture The Flag
  6. Nesting Time
  7. Back To Class
  8. Adding A Little Style
  9. Homework
By: icarus, (c) Melonfire
Rating: starstarstarstarstar / 19
February 27, 2002

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Now, the previous example was just fine for illustrative purposes - but if you're serious about plugging content into your Web site, you're going to need something a lot prettier. So take a look at this evolution of the previous script, which makes a few additions to simplify the task of formatting the RDF data.

<html> <head> <basefont face="Verdana"> </head> <body> <table border="0" cellspacing="5" cellpadding="5"> <tr> <td><b>New releases on freshmeat.net today:</b></td> </tr> <?php // XML file $file = "http://www.freshmeat.net/backend/fm-releases.rdf"; // set up some variables for use by the parser $currentTag = ""; $flag = ""; $count = 0; // this is an associative array of channel data with keys ("title", "link", "description") $channel = array(); // this is an array of arrays, with each array element representing an <item> // each outer array element is itself an associative array // with keys ("title", "link", "description") $items = array(); // opening tag handler function elementBegin($parser, $name, $attributes) { global $currentTag, $flag; $currentTag = $name; // set flag if entering <channel> or <item> block if ($name == "ITEM") { $flag = 1; } else if ($name == "CHANNEL") { $flag = 2; } } // closing tag handler function elementEnd($parser, $name) { global $currentTag, $flag, $count; $currentTag = ""; // set flag if exiting <channel> or <item> block if ($name == "ITEM") { $count++; $flag = 0; } else if ($name == "CHANNEL") { $flag = 0; } } // character data handler function characterData($parser, $data) { global $currentTag, $flag, $items, $count, $channel; $data = trim(htmlspecialchars($data)); if ($currentTag == "TITLE" || $currentTag == "LINK" || $currentTag == "DESCRIPTION") { // add data to $channels[] or $items[] array if ($flag == 1) { $items[$count][strtolower($currentTag)] .= $data; } else if ($flag == 2) { $channel[strtolower($currentTag)] .= $data; } } } // create parser $xp = xml_parser_create(); // set element handler xml_set_element_handler($xp, "elementBegin", "elementEnd"); xml_set_character_data_handler($xp, "characterData"); xml_parser_set_option($xp, XML_OPTION_CASE_FOLDING, TRUE); xml_parser_set_option($xp, XML_OPTION_SKIP_WHITE, TRUE); // read XML file if (!($fp = fopen($file, "r"))) { die("Could not read $file"); } // parse data while ($xml = fread($fp, 4096)) { if (!xml_parse($xp, $xml, feof($fp))) { die("XML parser error: " . xml_error_string(xml_get_error_code($xp))); } } // destroy parser xml_parser_free($xp); // now iterate through $items[] array // and print each item as a table row foreach ($items as $item) { echo "<tr><td><a href=" . $item["link"] . ">" . $item["title"] . "</a><br>" . $item["description"] . "</td></tr>"; } ?> </table> </body> </html>
The major difference between this iteration and the previous one is that this one creates two arrays to hold the information extracted during the parsing process. The $channel array is an associative array which holds basic descriptive information about the channel being processed, while the $items array is a two-dimensional array containing information on the individual channel items. Every element of the $items array is itself an associative array, with named keys for the item title, URL and description; the total number of elements in $items is equal to the total number of <item> blocks in the RDF document.

Note also the change to the $flag variable, which now holds two values depending on whether a <channel>...</channel> or <item>...</item> block is being processed. This is necessary so that the parser puts the information into the appropriate array.

Once the document has been fully parsed, it's a simple matter to iterate through the $items array and print each item as a table row. Here's what the end result looks like:



 
 
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