Basic usage
Many examples in this reference require an XML string. Instead of repeating this string in every example, we put it into a file which we include in each example. This included file is shown in the following example section. Alternatively, you could create an XML document and read it with simplexml_load_file().
Exemplo #1 Include file example.php with XML string
<?php
$xmlstr = <<<XML
<?xml version='1.0' standalone='yes'?>
<movies>
<movie>
<title>PHP: Behind the Parser</title>
<characters>
<character>
<name>Ms. Coder</name>
<actor>Onlivia Actora</actor>
</character>
<character>
<name>Mr. Coder</name>
<actor>El ActÓr</actor>
</character>
</characters>
<plot>
So, this language. It's like, a programming language. Or is it a
scripting language? All is revealed in this thrilling horror spoof
of a documentary.
</plot>
<great-lines>
<line>PHP solves all my web problems</line>
</great-lines>
<rating type="thumbs">7</rating>
<rating type="stars">5</rating>
</movie>
</movies>
XML;
?>The simplicity of SimpleXML appears most clearly when one extracts a string or number from a basic XML document.
Exemplo #2 Getting <plot>
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
echo $xml->movie[0]->plot; // "So this language. It's like..."
?>Accessing elements within an XML document that contain characters not permitted under PHP's naming convention (e.g. the hyphen) can be accomplished by encapsulating the element name within braces and the apostrophe.
Exemplo #3 Getting <line>
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
echo $xml->movie->{'great-lines'}->line; // "PHP solves all my web problems"
?>Exemplo #4 Accessing non-unique elements in SimpleXML
When multiple instances of an element exist as children of a single parent element, normal iteration techniques apply.
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
/* For each <movie> node, we echo a separate <plot>. */
foreach ($xml->movie as $movie) {
echo $movie->plot, '<br />';
}
?>Exemplo #5 Using attributes
So far, we have only covered the work of reading element names and their values. SimpleXML can also access element attributes. Access attributes of an element just as you would elements of an array.
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
/* Access the <rating> nodes of the first movie.
* Output the rating scale, too. */
foreach ($xml->movie[0]->rating as $rating) {
switch((string) $rating['type']) { // Get attributes as element indices
case 'thumbs':
echo $rating, ' thumbs up';
break;
case 'stars':
echo $rating, ' stars';
break;
}
}
?>Exemplo #6 Comparing Elements and Attributes with Text
To compare an element or attribute with a string or pass it into a function that requires a string, you must cast it to a string using (string). Otherwise, PHP treats the element as an object.
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
if ((string) $xml->movie->title == 'PHP: Behind the Parser') {
print 'My favorite movie.';
}
htmlentities((string) $xml->movie->title);
?>Exemplo #7 Comparing Two Elements
Two SimpleXMLElements are considered different even if they point to the same element since PHP 5.2.0.
<?php
$el1 = new SimpleXMLElement($xmlstr);
$el2 = new SimpleXMLElement($xmlstr);
var_dump($el1 == $el2); // false since PHP 5.2.0
?>Exemplo #8 Using XPath
SimpleXML includes built-in XPath support. To find all <character> elements:
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
foreach ($xml->xpath('//character') as $character) {
echo $character->name, 'played by ', $character->actor, '<br />';
}
?>'//' serves as a wildcard. To specify absolute paths, omit one of the slashes.
Exemplo #9 Setting values
Data in SimpleXML doesn't have to be constant. The object allows for manipulation of all of its elements.
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
$xml->movie[0]->characters->character[0]->name = 'Miss Coder';
echo $xml->asXML();
?>The above code will output a new XML document, just like the original, except that the new XML will change Ms. Coder to Miss Coder.
Exemplo #10 Adding elements and attributes
Since PHP 5.1.3, SimpleXML has had the ability to easily add children and attributes.
<?php
include 'example.php';
$xml = new SimpleXMLElement($xmlstr);
$character = $xml->movie[0]->characters->addChild('character');
$character->addChild('name', 'Mr. Parser');
$character->addChild('actor', 'John Doe');
$rating = $xml->movie[0]->addChild('rating', 'PG');
$rating->addAttribute('type', 'mpaa');
echo $xml->asXML();
?>The above code will output an XML document based on the original but having a new character and rating.
Exemplo #11 DOM Interoperability
PHP has a mechanism to convert XML nodes between SimpleXML and DOM formats. This example shows how one might change a DOM element to SimpleXML.
<?php
$dom = new domDocument;
$dom->loadXML('<books><book><title>blah</title></book></books>');
if (!$dom) {
echo 'Error while parsing the document';
exit;
}
$s = simplexml_import_dom($dom);
echo $s->book[0]->title;
?>User Contributed Notes
A quick tip on xpath queries and default namespaces. It looks like the XML-system behind SimpleXML has the same workings as I believe the XML-system .NET uses: when one needs to address something in the default namespace, one will have to declare the namespace using registerXPathNamespace and then use its prefix to address the otherwise in the default namespace living element.
<?php
$string = <<<XML
<?xml version='1.0'?>
<document xmlns="http://www.w3.org/2005/Atom">
<title>Forty What?</title>
<from>Joe</from>
<to>Jane</to>
<body>
I know that's the answer -- but what's the question?
</body>
</document>
XML;
$xml = simplexml_load_string($string);
$xml->registerXPathNamespace("def", "http://www.w3.org/2005/Atom");
$nodes = $xml->xpath("//def:document/def:title");
?>Using stuff like: is_object($xml->module->admin) to check if there actually is a node called "admin", doesn't seem to work as expected, since simplexml always returns an object- in that case an empty one - even if a particular node does not exist.
For me good old empty() function seems to work just fine in such cases.
CheersFrom the README file:
SimpleXML is meant to be an easy way to access XML data.
SimpleXML objects follow four basic rules:
1) properties denote element iterators
2) numeric indices denote elements
3) non numeric indices denote attributes
4) string conversion allows to access TEXT data
When iterating properties then the extension always iterates over
all nodes with that element name. Thus method children() must be
called to iterate over subnodes. But also doing the following:
foreach ($obj->node_name as $elem) {
// do something with $elem
}
always results in iteration of 'node_name' elements. So no further
check is needed to distinguish the number of nodes of that type.
When an elements TEXT data is being accessed through a property
then the result does not include the TEXT data of subelements.
Known issues
============
Due to engine problems it is currently not possible to access
a subelement by index 0: $object->property[0].If you need to output valid xml in your response, don't forget to set your header content type to xml in addition to echoing out the result of asXML():
<?php
$xml=simplexml_load_file('...');
...
...xml stuff
...
//output xml in your response:
header('Content-Type: text/xml');
echo $xml->asXML();
?>[Editor's Note: The SimpleXMLIterator class, however, does implement these methods.]
While SimpleXMLElement claims to be iterable, it does not seem to implement the standard Iterator interface functions like ::next and ::reset properly. Therefore while foreach() works, functions like next(), current(), or each() don't seem to work as you would expect -- the pointer never seems to move or keeps getting reset.If you're not sure the XML will be valid you'd better use:
<?php
$xmlObject = simplexml_load_string($xml);
// or
$xmlObject = simplexml_load_file(xml);
?>
Both of these return a SimpleXMLElement Object or a libXMLError Object.To test whether an element exists:
<?php
$xml = <<<EOT
<?xml version='1.0' standalone='yes'?>
<root>
<test1></test1>
<test2 />
<test4> </test4>
</root>
EOT;
$xmlDoc = new SimpleXMLElement($xml);
echo "Test1: \n";
var_dump($xmlDoc->test1);
echo "\n(" . (bool)$xmlDoc->test1 . ")";
echo "\n\n";
echo "Test2: \n";
var_dump($xmlDoc->test2);
echo "\n(" . (bool)$xmlDoc->test2 . ")";
echo "\n\n";
echo "Test3: \n";
var_dump($xmlDoc->test3);
echo "\n(" . (bool)$xmlDoc->test3 . ")";
echo "\n\n";
echo "Test4: \n";
var_dump($xmlDoc->test4);
echo "\n(" . (bool)$xmlDoc->test4 . ")";
echo "\n\n";
?>
The var_dumps for test1, test2, and test3 are identical, but the (bool) test gives a '1' for test1 and test2, and a '' for test3.