How to output in XML version and encoding (PHP) - php

Question

There is a plugin that forms an XML file for exporting goods. But no matter how hard I try, I can not insert the code <?xml version = "1.0" encoding = "utf-8"?> at the beginning of the line. Unfortunately, it is necessary for the validation of the file. Now produces this way:
<root>
<object>
<objectid></objectid>
<title></title>
<type></type>
...
</object>
<object>...</object>
...
</root>
I'm not a pro on this issue, but I will give only a piece of code in which the problem is possible:
public function onAjaxBTExport()
{
$xml = new SimpleXMLElementExtended('<root/>');
....
$data = $xml->asXML();
file_put_contents(JPATH_SITE.'/data.xml', $data);
header('Content-type: text/xml');
echo $data;
die;
}
class SimpleXMLElementExtended extends SimpleXMLElement
{
private function addCDataToNode(SimpleXMLElement $node, $value = '')
{
if ($domElement = dom_import_simplexml($node))
{
$domOwner = $domElement->ownerDocument;
$domElement->appendChild($domOwner->createCDATASection("{$value}"));
}
}
public function addChildWithCData($name = '', $value = '')
{
$newChild = parent::addChild($name);
if ($value) $this->addCDataToNode($newChild, "{$value}");
return $newChild;
}
public function addCData($value = '')
{
$this->addCDataToNode($this, "{$value}");
}
}

Answer 1

Consider running XSLT (the XML transformation language) using the identity tranform template which copies entire document as is and then explicitly set the omit-xml-declaration to "no". The added benefit of this is pretty printing your output.
To run XSLT 1.0 in PHP, be sure to enable the php-xsl extension in .ini file. Below XSLT is embedded as string but can be parsed from file.
$xml = new SimpleXMLElementExtended('<root/>');
...
$data = $xml->asXML();
// LOAD XML SOURCE
$doc = new DOMDocument;
$doc->loadXML($data);
// LOAD XSLT SOURCE
$xsl = new DOMDocument;
$xsl->loadXML('<xsl:transform xmlns:xsl="http://www.w3.org/1999/XSL/Transform" version="1.0">
<xsl:output version="1.0" encoding="UTF-8" omit-xml-declaration="no" indent="yes" />
<xsl:strip-space elements="*"/>
<!-- Identity Transform -->
<xsl:template match="#*|node()">
<xsl:copy>
<xsl:apply-templates select="#*|node()"/>
</xsl:copy>
</xsl:template>
</xsl:transform>');
// CONFIGURE TRANSFORMER
$proc = new XSLTProcessor;
$proc->importStyleSheet($xsl);
// RUN TRANSFORMATION
$newXML = $proc->transformToXML($doc);
// ECHO TO CONSOLE
header('Content-type: text/xml');
echo $newXML;
// SAVE TO FILE
file_put_contents(JPATH_SITE.'/data.xml', $newXML);