PHP DOMDocument not formatting output correctly

I'm currently working on the sitemaps for a website, and I'm using SimpleXML to import and do some checks on the original XML file. after this I use simplexml_load_file("small.xml"); to convert it to DOMDocument to make it easier to precisely add and manipulate XML elements. Below is the test XML sitemap that i'm working from:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:52:32-Orouke.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:53:23-castle technology.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:53:38-banana split.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:53:42-Waveney.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:55:12-pure orange.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:57:54-tau press.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:59:21-E.f.m.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:59:31-apple.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:59:45-townhouse communications.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
</urlset>

Now. here is the test code I'm using to modify:

<?php

$root = simplexml_load_file("small.xml");

$domRoot = dom_import_simplexml($root);

$dom = $domRoot->ownerDocument;

$urlElement = $dom->createElement("url");

    $locElement = $dom->createElement("loc");

        $locElement->appendChild($dom->createTextNode("www.google.co.uk"));

    $urlElement->appendChild($locElement);

    $lastmodElement = $dom->createElement("lastmod");

        $lastmodElement->appendChild($dom->createTextNode("2011-08-02"));

    $urlElement->appendChild($lastmodElement);

$domRoot->appendChild($urlElement);

$dom->formatOutput = true;
echo $dom->saveXML();

?>

The main problem is, that no matter where i place $dom->formatOutput = true; the existing XML that was imported from SimpleXML is formatted correctly, but anything new is formatted in the "all one line" style, as follows:

<?xml version="1.0" encoding="UTF-8"?>
<urlset xmlns="http://www.sitemaps.org/schemas/sitemap/0.9">
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:52:32-Orouke.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:53:23-castle technology.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:53:38-banana split.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:53:42-Waveney.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:55:12-pure orange.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:57:54-tau press.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    开发者_运维知识库<loc>http://www.companycheck.co.uk/searches/2011/08/22/23:59:21-E.f.m.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:59:31-apple.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
  <url>
    <loc>http://www.companycheck.co.uk/searches/2011/08/22/23:59:45-townhouse communications.html</loc>
    <lastmod>2011-08-23</lastmod>
  </url>
<url><loc>www.google.co.uk</loc><lastmod>2011-08-02</lastmod></url></urlset>

If anyone has an idea why this is happening and how to fix it I would be very grateful.

There is a workaround. You can force reformatting by saving your new xml to string first, then load it again after setting the formatOutput property, e.g.:

$strXml = $dom->saveXML();
$dom->formatOutput = true;
$dom->loadXML($strXml);
echo $dom->saveXML();

To format output nicely, you need to set the preserveWhiteSpace variable to false before loading as stated in the documentation

Example:

$Xhtml = "<div><span></span></div>";
$doc = new DOMDocument('1.0','UTF-8');
$doc->preserveWhiteSpace = false;
$doc->formatOutput = true;
$doc->loadXML($Xhtml);
$formattedXhtml = $doc->saveXML($doc->documentElement, LIBXML_NOXMLDECL);
$expectedFormatting =<<<EOF
<div>
  <span/>
</div>
EOF;
$this->assertEquals($expectedFormatting,$formattedXhtml,"The XHTML is formatted");   

Just for the visitor that comes here as this was the first answer on Google Search.

I had this same problem using code like Simon's.

Turns out that when you disable errors (either with $doc->loadHTML(..., LIBXML_NOERROR) or libxml_use_internal_errors(true);), it won't format anymore (example: https://3v4l.org/ur76E).

The solution is to not disable errors and suppress them on the PHP side (with @).

Ugly, but it works: https://3v4l.org/BSJVu

The final silver bullet function looks like:

function beautifyDoc(DOMDocument $doc): void
{
    $previousLibXmlState = libxml_use_internal_errors(false);
    $previousErrorHandler = set_error_handler(null);
    try {
        $html = $doc->saveHTML();
        $doc->preserveWhiteSpace = false;
        $doc->formatOutput = true;
        @$doc->loadHTML($html);
    } finally {
        libxml_use_internal_errors($previousLibXmlState);
        set_error_handler($previousErrorHandler);
    }
}

// usage
$doc = new DOMDocument();
// ...load html and do stuff...
beautifyDoc($doc);
echo $doc->saveHTML(); // done

(it also takes care of the php error handler, if already set)