simplexml.examples-basic|Basic SimpleXML usage | php教程

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Basic SimpleXML 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().

Example #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 Act&#211;r</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.

Example #2 Getting <plot>


<?php
include 'example.php';

$movies = new SimpleXMLElement($xmlstr);

echo $movies->movie[0]->plot;
?>

以上例程会输出：


   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.

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.

Example #3 Getting <line>


<?php
include 'example.php';

$movies = new SimpleXMLElement($xmlstr);

echo $movies->movie->{'great-lines'}->line;
?>

以上例程会输出：

PHP solves all my web problems

Example #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';

$movies = new SimpleXMLElement($xmlstr);

/* For each <character> node, we echo a separate <name>. */
foreach ($movies->movie->characters->character as $character) {
   echo $character->name, ' played by ', $character->actor, PHP_EOL;
}

?>

以上例程会输出：

Ms. Coder played by Onlivia Actora
Mr. Coder played by El Actór

Note:
Properties ($movies->movie in previous example) are not arrays. They are iterable and accessible objects.

Example #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';

$movies = new SimpleXMLElement($xmlstr);

/* Access the <rating> nodes of the first movie.
 * Output the rating scale, too. */
foreach ($movies->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;
    }
}
?>

以上例程会输出：

7 thumbs up5 stars

Example #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';

$movies = new SimpleXMLElement($xmlstr);

if ((string) $movies->movie->title == 'PHP: Behind the Parser') {
    print 'My favorite movie.';
}

echo htmlentities((string) $movies->movie->title);
?>

以上例程会输出：

My favorite movie.PHP: Behind the Parser

Example #7 Comparing Two Elements

Two SimpleXMLElements are considered different even if they point to the same element since PHP 5.2.0.


<?php
include 'example.php';

$movies1 = new SimpleXMLElement($xmlstr);
$movies2 = new SimpleXMLElement($xmlstr);
var_dump($movies1 == $movies2); // false since PHP 5.2.0
?>

以上例程会输出：

bool(false)

Example #8 Using XPath

SimpleXML includes built-in XPath support. To find all <character> elements:


<?php
include 'example.php';

$movies = new SimpleXMLElement($xmlstr);

foreach ($movies->xpath('//character') as $character) {
    echo $character->name, ' played by ', $character->actor, PHP_EOL;
}
?>

'//' serves as a wildcard. To specify absolute paths, omit one of the slashes.

以上例程会输出：

Ms. Coder played by Onlivia Actora
Mr. Coder played by El Actór

Example #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';
$movies = new SimpleXMLElement($xmlstr);

$movies->movie[0]->characters->character[0]->name = 'Miss Coder';

echo $movies->asXML();
?>

以上例程会输出：

<?xml version="1.0" standalone="yes"?>
<movies>
 <movie>
  <title>PHP: Behind the Parser</title>
  <characters>
   <character>
    <name>Miss Coder</name>
    <actor>Onlivia Actora</actor>
   </character>
   <character>
    <name>Mr. Coder</name>
    <actor>El Act&#xD3;r</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>

Example #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';
$movies = new SimpleXMLElement($xmlstr);

$character = $movies->movie[0]->characters->addChild('character');
$character->addChild('name', 'Mr. Parser');
$character->addChild('actor', 'John Doe');

$rating = $movies->movie[0]->addChild('rating', 'PG');
$rating->addAttribute('type', 'mpaa');

echo $movies->asXML();
?>

以上例程会输出：

<?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 Act&#xD3;r</actor>
   </character>
  <character><name>Mr. Parser</name><actor>John Doe</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>
 <rating type="mpaa">PG</rating></movie>
</movies>

Example #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;
}

$books = simplexml_import_dom($dom);

echo $books->book[0]->title;
?>

以上例程会输出：

blah

User Contributed Notes

dianarusu21 at gmail dot com 20-Oct-2017 09:16


Quick start with xml.



//PHP file:

<?php

$xml = simplexml_load_file("simpleXml.xml");



foreach ($xml as $key => $value) {

  foreach ($value as $key => $value) {

    echo $key.": ".$value."</br>";

  }

}

?>



//XML file:

<?xml version="1.0" encoding="UTF-8"?>

<locations>

  <country>

    <name>Romania</name>

    <capital>Bucharest</capital>

    <language>Romanian</language>

  </country>

  <country>

    <name>Frace</name>

    <capital>Paris</capital>

    <language>France</language>

  </country>

  <country>

    <name>Spain</name>

    <capital>Madrid</capital>

    <language>Spanish</language>

  </country>

</locations>



//Output:

// name: Romania

// capital: Bucharest

// language: Romanian

// name: Frace

// capital: Paris

// language: France

// name: Spain

// capital: Madrid

// language: Spanish



NOTE: You don't need to include the xml file in the php file..

Anonymous 22-Aug-2017 12:35


If your xml string contains booleans encoded with "0" and "1", you will run into problems when you cast the element directly to bool:



$xmlstr = <<<XML

<?xml version='1.0' standalone='yes'?>

<values>

    <truevalue>1</truevalue>

    <falsevalue>0</falsevalue>

</values>

XML;

$values = new SimpleXMLElement($xmlstr);

$truevalue = (bool)$values->truevalue; // true

$falsevalue = (bool)$values->falsevalue; // also true!!!



Instead you need to cast to string or int first:



$truevalue = (bool)(int)$values->truevalue; // true

$falsevalue = (bool)(int)$values->falsevalue; // false

rowan dot collins at gmail dot com 04-Jun-2015 06:58


There is a common "trick" often proposed to convert a SimpleXML object to an array, by running it through json_encode() and then json_decode(). I'd like to explain why this is a bad idea.



Most simply, because the whole point of SimpleXML is to be easier to use and more powerful than a plain array. For instance, you can write <?php $foo->bar->baz['bing'] ?> and it means the same thing as <?php $foo->bar[0]->baz[0]['bing'] ?>, regardless of how many bar or baz elements there are in the XML; and if you write <?php (string)$foo->bar[0]->baz[0] ?> you get all the string content of that node - including CDATA sections - regardless of whether it also has child elements or attributes. You also have access to namespace information, the ability to make simple edits to the XML, and even the ability to "import" into a DOM object, for much more powerful manipulation. All of this is lost by turning the object into an array rather than reading understanding the examples on this page.



Additionally, because it is not designed for this purpose, the conversion to JSON and back will actually lose information in some situations. For instance, any elements or attributes in a namespace will simply be discarded, and any text content will be discarded if an element also has children or attributes. Sometimes, this won't matter, but if you get in the habit of converting everything to arrays, it's going to sting you eventually.



Of course, you could write a smarter conversion, which didn't have these limitations, but at that point, you are getting no value out of SimpleXML at all, and should just use the lower level XML Parser functions, or the XMLReader class, to create your structure. You still won't have the extra convenience functionality of SimpleXML, but that's your loss.

mymymymy at mymymymy dot com 02-Jan-2015 09:41


$children = $xml->children();

var_dump($children[0]["@attributes"]);//"NULL"

var_dump($children[0]);//(2) ["@attributes"]=>array(1) {['x']=> string(1) '2'}



no faithfully (not true)

------

example:



SimpleXMLElement Object

(

    [@attributes] => Array

        (

            [name] => USA

        )

)



print_r($xml->country->attributes()->name);

show:

 SimpleXMLElement Object

(

    [0] => USA

)



print_r((string)$xml->country->attributes()->name);

show:

USA

RiKdnUA at mail dot ru 02-Dec-2013 09:40


Если кодировка XML-документа отличается от UTF-8, объявление кодировки должно следовать сразу после version='...' и перед standalone='...'. Это требование стандарта XML. 



If encoding XML-document differs from UTF-8. Encoding declaration should follow immediately after the version = '...' and before standalone = '...'. This requirement is standard XML. 



<?xml version='1.0' encoding='windows-1251' standalone='yes'?>

Ok

<?xml version='1.0' standalone='yes' encoding='windows-1251'?>

<body>Русский язык. Russian language</body>

Fatal error: Uncaught exception 'Exception' with message 'String could not be parsed as XML' in...

eng dot emad_2010 at yahoo dot com 08-Oct-2013 11:46


Example #  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  . 

The simplexml_import_dom() function returns a SimpleXMLElement object from a DOM node.

DOM         object



<?php

//create DOM  document $dom that contain XML

$dom = new DOMDocument;

$dom->loadXML('<books><book><title>blah</title></book></books>');

if (!$dom) {

    echo 'Error while parsing the document';

    exit;

}

//convert DOM document $dom to object $books 

$books = simplexml_import_dom($dom);



//access object $books 

echo $books->book[0]->title;

?>

jishcem at gmail dot com 12-Mar-2013 07:31


For me it was easier to use arrays than objects, 



So, I used this code, 



$xml = simplexml_load_file('xml_file.xml');

    

$json_string = json_encode($xml);

    

$result_array = json_decode($json_string, TRUE);



Hope it would help someone

gkokmdam at zonnet dot nl 23-Feb-2011 01:54


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");



?>

kdos 31-Jan-2011 05:32


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.



Cheers

Max K. 20-Jun-2010 02:38


From 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].

ie dot raymond at gmail dot com 01-Apr-2010 03:07


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();


?>

php at keith tyler dot com 23-Dec-2009 12:57


[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.

bjorn at xQmail dot eu 31-Aug-2009 07:48


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.

radams at circlepix com 24-Apr-2009 10:52


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.

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Basic SimpleXML usage

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