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SimpleXMLElement::xpath

(PHP 5, PHP 7, PHP 8)

SimpleXMLElement::xpath — Runs XPath query on XML data

说明

public SimpleXMLElement::xpath(string $expression): array|null|false

The xpath method searches the SimpleXML node for children matching the XPath expression.

参数

expression: An XPath path

返回值

Returns an array of SimpleXMLElement objects on success; or null or false in case of an error.

示例

示例 #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');

foreach ($result as $node) {
    echo '/a/b/c: ',$node,"\n";
}

/* Relative paths also work... */
$result = $xml->xpath('b/c');

foreach ($result as $node) {
    echo 'b/c: ',$node,"\n";
}
?>

以上示例会输出：

 
/a/b/c: text
/a/b/c: stuff
b/c: text
b/c: stuff

Notice that the two results are equal.

参见

SimpleXMLElement::registerXPathNamespace() - Creates a prefix/ns context for the next XPath query
SimpleXMLElement::getDocNamespaces() - Returns namespaces declared in document
SimpleXMLElement::getNamespaces() - Returns namespaces used in document
Basic SimpleXML usage

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User Contributed Notes 18 notes

down

leonjanzen at gmail dot com ¶

9 years ago

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

down

grummfy at gmail dot com ¶

13 years ago

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...

?>

down

drewish at katherinehouse dot com ¶

18 years ago

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"/>

down

anemik ¶

15 years ago

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.

        )

...

down

Anonymous ¶

8 years ago

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.

down

canuemail at gmail dot com ¶

15 years ago

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;

    }

    

}

?>

down

yetihehe at yetihehe dot com ¶

12 years ago

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

down

paul at pmtlogic dot com ¶

15 years ago

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']"); ?>

down

Filippo Vicari ¶

1 year ago

You can also search for siblings with a condition. For example immagine to need the title for a desidered language which with the two siblings tags in this XML file

<?xml version="1.0" encoding="UTF-8"?>
<IDOC BEGIN="1">
...
<PRODUCT SEGMENT="1">
    <PRODUCTCODE>005</PRODUCTCODE>
    <LANG>E</LANG>
    <TITLE>Name</TITLE>
    <LANG_ISO>EN</LANG_ISO>
</PRODUCT>
<PRODUCT SEGMENT="1">
    <PRODUCTCODE>005</PRODUCTCODE>
    <LANG>I</LANG>
    <TITLE>Name I</TITLE>
    <LANG_ISO>IT</LANG_ISO>
</PRODUCT>
...  
</IDOC>

Let's break it down
<?php
"//PRODUCT" // find product tag
"//PRODUCT/LANG[.='E']" // whithin it find lang == "E"
"//PRODUCT/LANG[.='E']/../"  // go up one step
"//PRODUCT/LANG[.='E']/../TITLE" // get the title Tag content

// Combined search and find siblings ----------------------------
$xml = simplexml_load_file("fname.xml");

// Search for the TITLE field which sibling is == "E" ----------
$title_E_array = $xml->xpath("//PRODUCT/LANG[.='E']/../TITLE"); // By default gives back an array of  SimpleXmlElement 
$title = (string) $xml->xpath("//PRODUCT/LANG[.='E']/../TITLE")[0]; // in this way saves only the value as a string
?>

down

awoerl at contentserv dot com ¶

6 years ago

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?

down

Alexis Peters ¶

7 years ago

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"

down

DrupalFocus at earthlink dot net ¶

13 years ago

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.

down

behnam@zwnj ¶

14 years ago

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

down

arealzone-czernobyl at yahoo dot de ¶

14 years ago

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;

?>

down

Hugh ¶

17 years ago

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).

down

-4

Anti Veeranna ¶

14 years ago

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

down

-2

stefan at efectos dot nl ¶

13 years ago

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());

?>

down

-3

BenjaminBeck at gmx dot de ¶

9 years ago

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; 
    } 
    
} 
?>

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