PHP
XML DOM Parser
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
below ("note.xml") will be used in our example:
<?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:
Example
<?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
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>";
}
?>
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.
If you want
to learn more about the XML DOM, please visit our XML tutorial.
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