Inserting a new line using DOM

I'm attempting to insert a new node into an XML document. I'm using simpleXML for most of the parsing but for this piece I need to use DOM. This is the function i'm using to make the addition

function simplexml_insert_after(SimpleXMLElement $sxe, SimpleXMLElement $insert, SimpleXMLElement $target)   
 {
    $target_dom = dom_import_simplexml($target)开发者_如何学编程;
    $target_dom->formatOutput = true;
    $target_dom->preserveWhiteSpace = false;
    $insert_dom = $target_dom->ownerDocument->importNode(dom_import_simplexml($insert), true);
    if ($target_dom->nextSibling) {
        return $target_dom->parentNode->insertBefore($insert_dom, $target_dom->nextSibling);
    } else {
        return $target_dom->parentNode->appendChild($insert_dom);
    }
}

And calling it like this:

$meta2 = new SimpleXMLElement("<meta/>");
$meta2->addAttribute('name', 'subject');
$meta2->addAttribute('value', $doc_id); 
$target = current($my_xml->xpath('//meta[last()]'));
simplexml_insert_after($my_xml, $meta2, $target);

My Problem is that its inserting the new node immediately after the target rather than on a new line so the resulting XML looks like this:

<meta content="a" name="ap-category"/>
<meta content="bx" name="ap-format"/><meta name="subject" value="urn:blah"/>

When I'd like it to look like this:

<meta content="a" name="ap-category"/>
<meta content="bx" name="ap-format"/>
<meta name="subject" value="urn:blah"/>

I've tried changing preserveWhiteSpace to true, but it did not help. How do i go about adding a new line before inserting that node?

edit Here is the fix that worked:

 function simplexml_insert_after(SimpleXMLElement $sxe, SimpleXMLElement $insert,SimpleXMLElement $target)   
 {
     $target_dom = dom_import_simplexml($target);
     $target_dom->formatOutput = true;
     $target_dom->preserveWhiteSpace = false;
     $insert_dom = $target_dom->ownerDocument->importNode(dom_import_simplexml($insert), true);
     if ($target_dom->nextSibling) {
          $result = $target_dom->parentNode->insertBefore($insert_dom, $target_dom->nextSibling);
          $target_dom->parentNode->insertBefore($target_dom->ownerDocument->createTextNode("\n"), $result);
          return $result
     } else {
          return $target_dom->parentNode->appendChild($insert_dom);
     }
}

Try to insert a textnode just before the element you want to insert, something like this:

function simplexml_insert_after(SimpleXMLElement $sxe, 
                                SimpleXMLElement $insert, 
                                SimpleXMLElement $target)   
{
    $target_dom = dom_import_simplexml($target);
    $target_dom->formatOutput = true;
    $target_dom->preserveWhiteSpace = false;

    $document = $target_dom->ownerDocument;
    $insert_dom = $document->importNode(dom_import_simplexml($insert), true);

    $parentNode = $target_dom->parentNode;
    if ($target_dom->nextSibling) {
        $result = $parentNode->insertBefore($insert_dom, $target_dom->nextSibling);
        $parentNode->insertBefore($document->createTextNode("\n"), $result);
        return $result
    } else {
        return $parentNode->appendChild($insert_dom);
    }
}

Try changing your method call to this:

simplexml_insert_after($my_xml, "\n" . $meta2, $target);

...with preserveWhiteSpace = true;