Simplexml in php 5

April 25, 2010

I found a new love in PHP — SimpleXML. I recently discovered I can traverse an XML tree just like I do in Actionscript, right in the middle of an HTML page. This makes it easy to create a website with all content in an XML document, a technique I like to use on projects that do not have the budget for a CMS. XML is useful for organizing site navigation and image/copy content in a central place, thus making it a breeze to update. You can then use SimpleXML to inject content into an HTML page with just a few lines of code.

According to the W3Schools:
“The SimpleXML function lets you convert XML to an object… This object can be processed, like any other object, with normal property selectors and array iterators.”

Using SimpleXML is as easy as loading the XML file and adding it to a SimpleXML object (this requires PHP 5):

$file = file_get_contents('navigation.xml');
$xml = new SimpleXMLElement($file);

Say you have your navigation organized in a basic XML file. It can be as simple or complex as you like; that’s the beauty of XML. My example below has attributes for page titles and URLs, which could easily be combined into one attribute and transformed accordingly with a PHP loop — for this example I kept them separate. Query strings are totally optional — it just depends on how you want to generate your subpage URLs (using $_GET or separate physical pages?).

// navigation.xml
<?xml version="1.0" encoding="UTF-8"?> 
    <page title="Home" url="index.php" />
    <page title="Projects" url="projects.php">
        <subpage title="Personal" query="personal" />
        <subpage title="Technical + Geeky" query="technical" />
        <subpage title="Creative" query="creative" />
    <page title="About Me" url="about.php" />
    <page title="Contact" url="contact.php" />

You can structure your XML file however you like by adding/removing child nodes and attributes to fit your website’s particular requirements. To generate HTML output from the XML file above, I like to use a foreach loop:

<div id="nav">
$file = file_get_contents('navigation.xml');
$xml = new SimpleXMLElement($file);
// for checking the current page 
$path = 'http://.'$_SERVER['HTTP_HOST'].'/';
// useful for generating full subpage URLs and preserving the domain in links 
$counter = 0;
echo "<ul>\n";
foreach($xml->children() as $page) {
   $numSubChildren = count($page->children());
   if($numSubChildren > 0) {  // add a class to <li>s with children 
   echo" class='hasChild'";
// form href from path and url attribute 
 echo"><a href='". $path . $page->attributes()->url. "' class='navLink";
// replace pesky ampersands in attributes 
$pageTitle = str_replace(' & ', ' &amp; ', $page->attributes()->title); 
// add class to current link 
 if(strstr($checkit, $page->getName()))  {
    echo " current'>".$pageTitle;
 else {
    echo "'>".$pageTitle;
echo "</a>\n";
if($numSubChildren > 0) {
echo " <li id='sub".$counter.">
   foreach($page->children() as $subpage) {
// loop through subpages 
$subtitle = str_replace('&','&amp;',$subpage->attributes()->title);
echo " <li class=\"subLi\"><a href='".$path.$page->attributes()->url."/".$subpage->attributes()->query;
// this method uses URL rewriting, but can also be used with plain query strings
// ?subpage=$subpage->attributes()->query; 
echo "' class='navLink'>".$subtitle."</a><li>\n";
echo "  </ul>\n";
echo "  <li>\n";
echo " </ul>\n";

I love this method because it is so simple to use — but it has potential to grow into complex code, as you can see. Holler at me if you have any questions or if you find this useful!