XML DOM

What is DOM

DOM provides a standard set of objects for HTML and XML documents, and a standard interface for accessing and manipulating them.

DOM is separated into different parts (Core, XML, and HTML) and different levels (DOM Level 1/2/3):

* Core DOM - defines a standard set of objects for any structured document
* XML DOM - defines a standard set of objects for XML documents
* HTML DOM - defines a standard set of objects for HTML documents

XML Parsing

To read and update - create and manipulate - an XML document, you will need an XML parser.

There are two basic types of XML parsers:

* Tree-based parser: This parser transforms an XML document into a tree structure. It analyzes the whole document, and provides access to the tree elements
* Event-based parser: Views an XML document as a series of events. When a specific event occurs, it calls a function to handle it

The DOM parser is an tree-based parser.

Look at the following XML document fraction:

Example:

<?xml version="1.0" encoding="ISO-8859-1"?>

<from>Jani</from>

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

An XML File

The XML file below will be used in our example:

Example:

<?xml version="1.0" encoding="ISO-8859-1"?>

<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:

Example:

<?php

$xmlDoc = new DOMDocument();

$xmlDoc->load("note.xml");



print $xmlDoc->saveXML();

?>

Looping through XML

We want to initialize the XML parser, load the XML, and loop through all elements of the <note> element:

Example:

<?php

$xmlDoc = new DOMDocument();

$xmlDoc->load("note.xml");



$x = $xmlDoc->documentElement;

foreach ($x->childNodes AS $item)

  {

  print $item->nodeName . " = " . $item->nodeValue . "<br />";

  }

?>

XML DOM

What is DOM

XML Parsing

Installation

An XML File

Load and Output XML

Looping through XML

Web Tutorials