12.4.1. Problem

12.4.2. Solution

$dom = domxml_open_file('books.xml');

Here's how to read XML from a variable:

$dom = domxml_open_mem($books);

$root = $dom->document_element( );

function process_node($node) {
    if ($node->has_child_nodes( )) {
        foreach($node->child_nodes( ) as $n) {
            process_node($n);
        }
    }

    // process leaves
    if ($node->node_type( ) =  = XML_TEXT_NODE) {
        $content = rtrim($node->node_value( ));
        if (!empty($content)) {
            print "$content\n";
        }
    }

}
process_node($root);

12.4.3. Discussion

// $node is the DOM parsed node <book cover="soft">PHP Cookbook</book>
$type = $node->node_type();

switch($type) { 
case XML_ELEMENT_NODE:
    // I'm a tag. I have a tagname property.
    print $node->node_name();  // prints the tagname property: "book" 
    print $node->node_value(); // null
    break;
case XML_ATTRIBUTE_NODE:
    // I'm an attribute. I have a name and a value property.
    print $node->node_name();  // prints the name property: "cover"
    print $node->node_value(); // prints the value property: "soft"
    break;
case XML_TEXT_NODE:
    // I'm a piece of text inside an element.
    // I have a name and a content property.
    print $node->node_name();  // prints the name property: "#text"
    print $node->node_value(); // prints the content property: "PHP Cookbook"
    break;
default:
    // another type
    break;
}

<books>
    <book>
        <title>PHP Cookbook</title>
        <author>Sklar</author>
        <author>Trachtenberg</author>
        <subject>PHP</subject>
    </book>
    <book>
        <title>Perl Cookbook</title>
        <author>Christiansen</author>
        <author>Torkington</author>
        <subject>Perl</subject>
    </book>
</books>

Here's how to find all authors:

// find and print all authors
$authors = $dom->get_elements_by_tagname('author');

// loop through author elements
foreach ($authors as $author) { 
    // child_nodes( ) hold the author values
    $text_nodes = $author->child_nodes( );

    foreach ($text_nodes as $text) {    
         print $text->node_value( );
    }
    print "\n";
}

The get_elements_by_tagname( ) function returns an array of element node objects. By looping through each element's children, you can get to the text node associated with that element. From there, you can pull out the node values, which in this case are the names of the book authors, such as Sklar and Trachtenberg.

12.4.4. See Also