Using PHP with XML (part 2) - Meet Joe Cool (
Page 2 of 6 )
As before, the
first order of business is to read the XML data into memory. PHP offers three
functions to do this: the xmldoc() and xmltree() functions accept a string containing
XML data as argument, and build a tree structure from that string, while the xmldocfile()
function accepts a filename as argument, and builds a DOM tree after reading the
data in the file.
<?
// create an XML-compliant string
$XMLDataString = "<?xml version="1.0"?"
. "><me><name>Joe
Cool</name><age>24</age><sex>male</sex></me>";
//
create a document object
$XMLDoc = xmldoc($XMLDataString);
// create a tree object
$XMLTree
= xmltree($XMLDataString);
?>
You can also load a file directly.
<?
// data file
$XMLFile = "me.xml";
// create a document object
$XMLDoc
= xmldocfile($XMLFile);
?>
Windows users should note that xmldocfile() needs the complete path to the file,
including drive letter, to work correctly.{mospagebreak title=Parents And Their
Children} Once the document has been read in, a number of methods become available
to traverse the document tree.
If you're using a document object, such as the one returned by xmldoc() and xmldocfile(),
you can use the following methods to obtain references to other nodes in the tree,
<?
// data file
$file = "library.xml";
// create a document object
$dom
= xmldocfile($file);
// echo these values to see the object type
// get root
node
$dom->root();
// get children under the root node as array
$dom->children();
?>
or to properties of the document itself.
<?
// data file
$file = "library.xml";
// create a document object
$dom
= xmldocfile($file);
// get XML version
echo $dom->version;
// get XML encoding
echo
$dom->encoding;
// get whether standalone file
echo $dom->standalone;
// get
XML URL
echo $dom->url;
// get XML character set
echo $dom->charset;
?>
Once you've obtained a reference to a node, a number of other methods and properties
become available to help you obtain the name and value of that node, as well as
references to parent and child nodes. Take a look:
<?
// data file
$str = "<?xml version="1.0"?><me><name>Joe
Cool</name><age>24</age><sex>male</sex></me>";
//
create a document object
$dom = xmldoc($str);
// get reference to root node
$root
= $dom->root();
// get name of node - "me"
echo $root->name;
// get children
of node, as array
$children = $root->children();
// get first child node
$firstChild
= $children[0];
// let's see a few node properties
// get name of first child
node - "name"
echo $firstChild->name;
// get content of first child node - "Joe
Cool"
echo $firstChild->content;
// get type of first child node - "1", or "XML_ELEMENT_NODE"
echo
$firstChild->type;
// go back up the tree!
// get parent of child - this should
be <me>
$parentNode = $firstChild->parent();
// check it...yes, it is "me"!
echo
$parentNode->name;
?>
A quick note on the "type" property above: every node is of a specific type,
and this property returns a numeric and textual code corresponding to the type.
A complete list of types is available in the PHP manual.{mospagebreak title=Welcome
To The Human Race} Many of the object methods you just saw are also available
as regular functions; for example,
<?
// data file
$str = "<?xml version="1.0"?><me><name>Joe
Cool</name><age>24</age><sex>male</sex></me>";
//
create a document object
$dom = xmldoc($str);
// get reference to root node
$root
= $dom->root();
// get name of node - "me"
echo $root->name;
// you could also
do this!
// get reference to root node
$root = domxml_root($dom);
// get name
of node - "me"
echo $root->name;
?>
Finally, element attributes may be obtained using either the $node->attributes()
object method, or the dom_attributes() function.
<?
// data file
$str = "<?xml version="1.0"?><me species="human"><name>Joe
Cool</name><age>24</age><sex>male</sex></me>";
//
create a document object
$dom = xmldoc($str);
// get reference to root node
$root
= $dom->root();
// get attribute collection
// $attributes = $root->attributes();
//
you could also do this!
// $attributes = domxml_attributes($root);
// get first
attribute name - "species"
echo $attributes[0]->name;
// get first attribute
value - "human"
echo $attributes[0]->children[0]->content;
// you could also
do this!
// echo domxml_getattr($root, "species");
?>
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