(PHP 5, PHP 7)
SimpleXMLElement::xpath — Runs XPath query on XML data
$path
) : array
The xpath method searches the SimpleXML node for
children matching the XPath path.
pathAn XPath path
Returns an array of SimpleXMLElement objects or FALSE in
case of an error.
Example #1 Xpath
<?php
$string = <<<XML
<a>
<b>
<c>text</c>
<c>stuff</c>
</b>
<d>
<c>code</c>
</d>
</a>
XML;
$xml = new SimpleXMLElement($string);
/* Search for <a><b><c> */
$result = $xml->xpath('/a/b/c');
while(list( , $node) = each($result)) {
echo '/a/b/c: ',$node,"\n";
}
/* Relative paths also work... */
$result = $xml->xpath('b/c');
while(list( , $node) = each($result)) {
echo 'b/c: ',$node,"\n";
}
?>
以上例程会输出：
/a/b/c: text /a/b/c: stuff b/c: text b/c: stuff
Notice that the two results are equal.
I tried to use string functions in the xpath statements I'm passing, like
$oXml->xpath('substring(/foo/bar/text(), 0, 4)');
But no matter which syntax I'm trying I never the string functions to work.
Is it possible, that the xpath method does not support function calls?
If you want this behavior for an multidimensional array you can use this:
<?php
function apath(&$a, $path, $value = NULL) {
$pathes = explode('/',$path);
if(count($pathes) > 1) {
$firstPart = array_shift($pathes);
if(!isset($a[$firstPart])) {
$a[$firstPart] = array();
}
return apath($a[$firstPart], implode('/', $pathes), $value);
} else {
if($value){
$a[$path] = $value;
} else {
return $a[$path];
}
}
}
apath($a, 'user/name', array('prename' => 'foo', 'lastname' => 'bar'));
$a = array();
var_dump($a);
var_dump(apath($a, 'user/name/lastname'));
?>
Gives you this:
array(1) {
["user"]=>
array(1) {
["name"]=>
array(2) {
["prename"]=>
string(5) "foo"
["lastname"]=>
string(8) "bar"
}
}
}
string(8) "bar"
As mentioned already xpath will fail is the default namespace 'xmlns' is used like in:
<?php
$xmlstring = $string = <<<XML
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<workbook xmlns="http://schemas.openxmlformats.org/spreadsheetml/2006/main">
<fileVersion appName="xl" />
</workbook>
XML;
?>
xpath cannot search through the xml without explicitly specifying a namespace.
There are 2 options :
1. rename the 'xmlns' into something else to trick xpath into believing that no default namespace is defined.
2. register a string as the default namespace and use that string in all your queries. Unfortunatly, an empty space will not work.
No other option currently exist until XPath2.0 becomes the default library.
To run an xpath query on an XML document that has a namespace, the namespace must be registered with SimpleXMLElement::registerXPathNamespace() before running the query. If the XML document namespace does not include a prefix, you must make up an arbitrary one, and then use it in your query.
<?php
$strXml= <<<XML
<?xml version="1.0" encoding="UTF-8"?>
<mydoc xmlns="http://www.url.com/myns">
<message>Test message</message>
</mydoc>
XML;
$xmlDoc=new \SimpleXMLElement($strXml);
foreach($xmlDoc->getDocNamespaces() as $strPrefix => $strNamespace) {
if(strlen($strPrefix)==0) {
$strPrefix="a"; //Assign an arbitrary namespace prefix.
}
$xmlDoc->registerXPathNamespace($strPrefix,$strNamespace);
}
print($xmlDoc->xpath("//a:message")[0]); //Use the arbitrary namespace prefix in the query.
?>
This will output:
Test message
If you want to search multiple values from xml on the behalf or one value then this code can be helpfull to you.
if there is:
<Record>
<country>Pakistan</country>
<code>+92</code>
<Value>100<Value>
</Record>
then try this one:
<?php
$sxe = simplexml_load_file("countries.XML");
foreach($sxe->xpath('//RECORD') as $item) {
$v = $row->xpath('./country[. ="Pakistan"]');
if($v[0]){
print $item->country;
print $item->code;
print $item->value;
}
}
?>
Xpath actually knows which element is root regardless of element on which you execute it. Example:
<?php
$string = <<<XML
<a>
<b>
<c>text</c>
<c>stuff</c>
</b>
<b>
<c>code</c>
</b>
</a>
XML;
header('content-type: text/plain');
$xml = new SimpleXMLElement($string);
//relative to root
$b0=$xml->b[0]->xpath('//c');
while(list( , $node) = each($b0)) {
echo 'b[0]: //c: ',$node,"\n";
}
$b1=$xml->b[1]->xpath('//c');
while(list( , $node) = each($b1)) {
echo 'b[1]: //c: ',$node,"\n";
}
echo "\n";
//relative to current element
$b0=$xml->b[0]->xpath('.//c');
while(list( , $node) = each($b0)) {
echo 'b[0]: .//c: ',$node,"\n";
}
$b1=$xml->b[1]->xpath('.//c');
while(list( , $node) = each($b1)) {
echo 'b[1]: .//c: ',$node,"\n";
}
?>
Will return:
b[0]: //c: text
b[0]: //c: stuff
b[0]: //c: code
b[1]: //c: text
b[1]: //c: stuff
b[1]: //c: code
b[0]: .//c: text
b[0]: .//c: stuff
b[1]: .//c: code
Having problems selecting information through xpath when there are namespaces in the XML?
Try this quick and dirty solution, but it works:
<?php
$objImageXml = new SimpleXMLElement($objImageXml->asXML());
?>
On a xml that have namespace you need to do this before your xpath request (or empty array will be return) :
<?php
$string = str_replace('xmlns=', 'ns=', $string); //$string is a string that contains xml...
?>
Looks like the relative path is relative to the SimpleXMLElement object that you call the Xpath() method on. Basically chopping off the root element.
<?php
$string = <<<XML
<foo>
<bar>
<a>
<b>
<c>text</c>
<c>stuff</c>
</b>
<d>
<c>code</c>
</d>
</a>
</bar>
</foo>
XML;
$xml = new SimpleXMLElement($string);
/* Search for children using 2nds level relative <bar><a><b><c> */
$result = $xml->xpath('a/b/c');
if ($result)
foreach($result as $node) {
drupal_set_message(t('a/b/c: @node.', array('@node' => $node)));
}
else
drupal_set_message(t('a/b/c: failed.'));
/* it relative to the SimpleXMLElement Search for 2nds level relative <bar><a><b><c> but where is foo */
$bar = $xml->bar;
$result = $bar->xpath('a/b/c');
foreach($result as $node) {
drupal_set_message(t('bar->a/b/c: @node.', array('@node' => $node)));
}
?>
results in :
#
# a/b/c: failed.
# bar->a/b/c: text.
# bar->a/b/c: stuff.
Seems like this function cannot return the result of XPath string() [1] function. For example if you query xpath("string(a/@b)") you will get bool(false) although the node "a" may have the attribute "b" set to a non-empty string.
[1] http://www.w3.org/TR/xpath#section-String-Functions
Whether it returns a false or empty array for a non-existing path seems to depend on libxml version.
I tried the following code:
<?php
$data = '<foo><bar></bar></foo>';
$xml = simplexml_load_string($data);
print gettype($xml->xpath('/first/second'));
?>
On a machine with libxml 2.6.16 and PHP 5.2.8 I got back boolean. On a different machine with libxml 2.7.3 and PHP 5.2.8/5.2.9 I got back empty array.
You can check the libxml version from command line by executing: php --ri libxml
or simply look at phpinfo() output
The simplest way to count nodes in a XML doc:
<?php
$xml = new SimpleXMLElement($xmlstr);
$xmlNode = $xml->xpath('root/yourNodeName');
$nodeCount = count($xmlNode);
echo $nodeCount;
?>
If you want to find easly all records satisfying some condition in XML data like
....
<book id="bk101">
<author>Gambardella, Matthew</author>
<title>XML Developer's Guide</title>
<genre>Computer</genre>
<price>44.95</price>
</book>
<book id="bk102">
<author>Ralls, Kim</author>
<title>Midnight Rain</title>
<genre>Fantasy</genre>
<price>5.95</price>
</book>
...
try example below
<?php
$xmlStr = file_get_contents('data/books.xml');
$xml = new SimpleXMLElement($xmlStr);
// seach records by tag value:
// find all book records with price higher than 40$
$res = $xml->xpath("book/price[.>'40']/parent::*");
print_r($res);
?>
You will see response like:
Array (
[0] => SimpleXMLElement Object
(
[@attributes] => Array
(
[id] => bk101
)
[author] => Gambardella, Matthew
[title] => XML Developer's Guide
[genre] => Computer
[price] => 44.95
[publish_date] => 2000-10-01
[description] => An in-depth look at creating applications
with XML.
)
...
xpath doesn't seem to be able to handle single quotes embedded in the query itself. For instance, I want to find geo coordinates in an xml file based on country name.
xml snippet:
<zones>
<zone country="Cote d'Ivoire" fullName="Yamoussoukro" geo="6.82,-5.28" id="1050"><url prefix="1001" value="fiji.html" /><url prefix="1002" value="C" /></zone>
</zones>
The following code does not work:
<?php
$xml = simplexml_load_file("my.xml");
$result = $xml->xpath("//zone[@country='Cote d\'Ivoire']");
foreach ( $result[0]->attributes() as $key => $val ) {
print "<div class='coords'>$key: $val</div>\n";
}
?>
I have tried many variations on the embedded single quote (i.e. escape codes) but with no result. W3C offers no explanation either.
In addition, there doesn't seem to be any way of embedding wildcards in the attribute value (you can embed wildcards in the attribute name). Otherwise the following might be a reasonable substitute in this context:
<?php $result = $xml->xpath("//zone[@country='Cote d*Ivoire']"); ?>
If you want to search multiple values from xml on the behalf or one value then this code can be helpfull to you.
if there is:
<Record>
<country>Pakistan</country>
<code>+92</code>
<Value>100<Value>
</Record>
then try this one:
<?php
$sxe = simplexml_load_file("countries.XML");
foreach($sxe->xpath('//RECORD') as $item) {
$row = simplexml_load_string($item->asXML());
$v = $row->xpath('//country[. ="Pakistan"]');
if($v[0]){
print $item->country;
print $item->code;
print $item->value;
}
}
?>
Note that this function does not ALWAYS return an array. It seems that if the specified path is not found in the document, it will return false. You need to check for the false value before using foreach, if you wish to avoid a warning (and often to handle errors or control program flow in this situation).
xpath() can also be used to select elements by their attributes. For a good XPath reference check out: http://www.w3schools.com/xpath/xpath_syntax.asp
<?php
$string = <<<XML
<sizes>
<size label="Square" width="75" height="75" />
<size label="Thumbnail" width="100" height="62" />
<size label="Small" width="112" height="69" />
<size label="Large" width="112" height="69" />
</sizes>
XML;
$xml = simplexml_load_string($string);
$result = $xml->xpath("//size[@label='Large']");
// print the first (and only) member of the array
echo $result[0]->asXml();
?>
The script would print:
<size label="Large" width="112" height="69"/>