设置formatOuput属性重新加载并生成一次
For anyone else who has been having issues with formatOuput not working, here is a work-around:
rather than just doing something like:
<?php
$outXML = $xml->saveXML();
?>
force it to reload the XML from scratch, then it will format correctly:
<?php
$outXML = $xml->saveXML();
$xml = new DOMDocument();
$xml->preserveWhiteSpace = false;
$xml->formatOutput = true;
$xml->loadXML($outXML);
$outXML = $xml->saveXML();
?>