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9.5 PHP XML DOM

The built-in DOM parser makes it possible to process XML documents in PHP.

The XML DOM Parser

The DOM parser is a tree-based parser.
Look at the following XML document fraction:

<?xml version="1.0" encoding="UTF-8"?>
<from>Jani</from>

The DOM sees the XML above as a tree structure:
- Level 1: XML Document
- Level 2: Root element: <from>
- Level 3: Text element: "Jani"

Installation

The DOM parser functions are part of the PHP core. There is no installation needed to use these functions.

The XML File

The XML file "note.xml" will be used in the example below:

<?xml version="1.0" encoding="UTF-8"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>

Load and Output XML

We want to initialize the XML parser, load the xml, and output it:

<?php
$xmlDoc = new DOMDocument();
$xmlDoc->load("note.xml");

print $xmlDoc->saveXML();
?>

The output of the code above will be:

Tove Jani Reminder Don't forget me this weekend!

If you select "View source" in the browser window, you will see the following HTML:

<?xml version="1.0" encoding="UTF-8"?>
<note>
<to>Tove</to>
<from>Jani</from>
<heading>Reminder</heading>
<body>Don't forget me this weekend!</body>
</note>

The example above creates a DOMDocument-Object and loads the XML from "note.xml" into it.
Then the saveXML() function puts the internal XML document into a string, so we can output it.

Looping through XML

<?php
$xmlDoc = new DOMDocument();
$xmlDoc->load("note.xml");

$x = $xmlDoc->documentElement;
foreach ($x->childNodes AS $item) {
  print $item->nodeName . " = " . $item->nodeValue . "<br>";
}
?>

The output of the code above will be:

#text =
to = Tove
#text =
from = Jani
#text =
heading = Reminder
#text =
body = Don't forget me this weekend!
#text =

In the example above you see that there are empty text nodes between each element.
When XML generates, it often contains white-spaces between the nodes. The XML DOM parser treats these as ordinary elements, and if you are not aware of them, they sometimes cause problems.

PHP Fundamentals course home
Module 9. PHP XML

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Example files created in this module:
PHP SimpleXML Parser - Read From String part 1 PHP SimpleXML Parser - Read From String part 2 note.xml PHP SimpleXML - Read From File PHP SimpleXML - Get Node Values books.xml PHP SimpleXML - Get Node Values of Specific Elements PHP SimpleXML - Get Node Values - Loop PHP SimpleXML - Get Attribute Values menubar1.xml test menu (9) PHP SimpleXML - Get Attribute Values - Loop PHP XML Expat - The XML Expat Parser