Remove elements from XML without blank lines in one step (with PHP) - php

Question

I have a XML where I delete some elements. After that I get some blank lines so I take a second step to remove them with preserveWhiteSpace = false.
My code is like this now:
<?php
// erase elements
$docX->loadXML("events.xml");
$docX = new SimpleXMLElement($docX);
for ($o = count($docX->event); $o >= 0 ; $o--) {
if ($docX->event[$o]->typ == 'old') {
unset($docX->event[$o]);
}
}
file_put_contents("events_new.xml", $docX->saveXML());
// clean blank lines
$file = "events_new.xml";
$fp = fopen($file, "rb") or die("cannot open file");
$str = fread($fp, filesize($file));
$xml = new DOMDocument();
$xml->formatOutput = true;
$xml->preserveWhiteSpace = false;
$xml->loadXML($str) or die("Error");
file_put_contents("events_new.xml", $xml->saveXML());
?>
Is it possible to do this in one step?

Answer 1

I see this a follow-up to your earlier question. Hence, I usually recommend any XML manipulation should be done with an XSLT solution. XSLT is a special purpose declarative language that transforms XML files into any needed format. Most programming languages including PHP (uncomment the XSL extension in .ini file), Java, C, Python, VBA maintain XSLT libraries.
Either you can load the XSLT externally in an .xsl file or internally as a string as below example shows with DOMDocument. Notice too the line to strip space and indent. Another reason to consider this route is if parsing XML files is more complex than filtering off node values (i.e., grouping elements, assigning new ids, filtering by attributes):
// Load the XML source
$xml = new DOMDocument;
$xml->load('events.xml');
// Load the XSL string
$xsl = new DOMDocument;
$xslstr = "<?xml version=\"1.0\"?>
<xsl:stylesheet version=\"1.0\"
xmlns:xsl=\"http://www.w3.org/1999/XSL/Transform\">
<xsl:strip-space elements=\"*\" />
<xsl:output method=\"xml\" indent=\"yes\" encoding=\"UTF-8\" />
<xsl:template match=\"events\">
<xsl:element name=\"event\">
<xsl:for-each select=\"event/typ[text()='new']\">
<xsl:copy-of select=\"..\"/>
</xsl:for-each>
</xsl:element>
</xsl:template>
</xsl:stylesheet>";
$xsl->loadXML($xslstr);
// Configure the transformer
$proc = new XSLTProcessor;
// attach the XSL rules
$proc->importStyleSheet($xsl);
// Transform XML source
$newXml = $proc->transformToXML($xml);
// Save output to file
file_put_contents('events_new.xml', $newXml);