SimpleXMLElement::asXML()

(PHP 5, PHP 7)

Return a well-formed XML string based on SimpleXML element

说明

publicSimpleXMLElement::asXML([string $filename]): mixed

TheasXMLmethod formats the parent object's data in XML version 1.0.

参数

$filename: If specified, the function writes the data to the file rather than returning it.

返回值

If the$filenameisn't specified, this function returns a string on success and FALSE on error. If the parameter is specified, it returns TRUE if the file was written successfully and FALSE otherwise.

范例

Example #1 Get XML

<?php
$string = <<<XML
<a>
 <b>
  <c>text</c>
  <c>stuff</c>
 </b>
 <d>
  <c>code</c>
 </d>
</a>
XML;
$xml = new SimpleXMLElement($string);
echo $xml->asXML();
?>

以上例程会输出：

<?xml version="1.0"?>
<a>
 <b>
  <c>text</c>
  <c>stuff</c>
 </b>
 <d>
  <c>code</c>
 </d>
</a>

asXMLalso works on Xpath results:

Example #2 Using asXML()on SimpleXMLElement::xpath() results

<?php
// Continued from example XML above.
/* Search for <a><b><c> */
$result = $xml->xpath('/a/b/c');
foreach ($result as $node) {
    echo $node->asXML();
}
?>

以上例程会输出：

<c>text</c><c>stuff</c>

参见

SimpleXMLElement::__toString() Returns the string content
Basic SimpleXML usage

To prevent asXML from encoding vowels unwantedly, simply use an approriate XML header with encoding in advance.
If you do so, asXML will happily leave your vowels (and the header) entirely untouched.
<?php
$xmlstr =
'<?xml version="1.0" encoding="UTF-8"?>
<keys>
 <key lang="en">&lt;Insert&gt;</key>
 <key lang="de">&lt;Einfügen&gt;</key>
</keys>';
$sxe = new SimpleXMLElement($xmlstr);
$output = $sxe->asXML();
?>
$xmlstr and $output are identical now.
The subsequent use of html_entity_decode() (as proposed in the very beginning in another post) has several drawbacks:
1. It is slow
2. It is expensive
3. If there are already encoded arrow brackets or double quotes in your source for instance (as shown in the above example), markup will be broken.

Function asXML decodes special chars like ø, æ and others to &#xE6;, &#xF8;
To get normal output use without quoting:
$xml = html_entity_decode($xml, ENT_NOQUOTES, 'UTF-8');

Code snippet to load a XML document, increment an attribute and store it again.
My XML looks like:
<?xml version="1.0" encoding="ISO-8859-1"?>
<doctypes counter="16">
  <doctype id="d1">
    <name>Carta</name>
    <acro>CA</acro>
  </doctype>
...
</doctypes>
I want to retrieve the counter attribute, increment it, and store the new document at the end:
<?php
 $document = simplexml_load_file("mydoc.xml");
 $cont = (integer) $document['counter'];
 $document['counter'] = $cont+1;
 $document->asXML("mydoc.xml");
?>