Harness XML with PHP 5 extensions

A time to query

Parse the XML

To parse the XML document catalog.xml create a PHP file, parseXML.php. Create a DOMDocument object. Load the example XML document using load(String xmlFile). Another function loadXML(string xmlDocument) may be used to load an XML document from a String.

$domDocument->load("file://C:/PHP/catalog.xml");

As an example, obtain all the title nodes in the XML document using getElementsByTagName(string tagName). Iterate over the node list and output the title elements' values.

$titleNodeList=$domDocument->getElementsByTagName("title");
   for($i=0; $I<$titleNodeList->length;$i++)
   {
     echo $titleNodeList->item($i)->nodeValue;
     print "<br/>\n";
     
    }

The output from the PHP script is shown below.

The Java XPath API
JAXP validation

Navigate XML with XPath

To navigate the XML document using XPath create a PHP script, xpath.php. Create a DOMDocument object and load the example XML document with load(string filename).

The DOMXPath class is used to evaluate an XPath expression in the context of an XML document node. Create a DOMXPath object.

$domXPath=new DOMXPath($domDocument);

XPath expressions may be evaluated with query(). Parameter of type DOMNode is optional in query(). By default the context node is the root element. As an example, retrieve the values of all the title elements.

$titles=$domXPath->query("/catalog/journal/article/title");

The query() returns a DOMNodeList. Iterate over the DOMNodeList to output the values of the title elements.

foreach ($titles as $title) {

    echo 'Title: ', $title->firstChild->nodeValue;
    print "<br/>\n";
}

The output from the xpath.php script is shown below.

Title: The Java XPath API
Title: JAXP validation

Validate your XML

In this section we validate the example document with an XML schema, catalog.xsd. The schema validation functions, schemaValidate(string filename) and schemaValidateSource(string schema), return a boolean value indicating if an XML document is valid. Limitations of the schema validation functions are that only one schema may be specified for validation and that the detail of the validation error is not output.

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