PHP XML node coping

Question

I'm really frustrated now since I do not seem to understand why it is that difficult to copy a node (with all the childs) from one XML tree to another.

I googled alot and it seems that I have to read the trees in with SimpleXML and then parse the nodes to DOM to import/export them somehow. Should there be a function doing this in one rush?

Basically I want to copy from the source all processList->process entries to destination test->processList-> .

source:
<processList>
    <process ...>
        //some more child nodes
    </process>
</processList>

destination:
<test>
    <processList>
        <process ...>
            //some more child nodes
        </process>
    </processList>
</test>

Can someone please advise?

php.net/manual/en/domdocument.importnode.php

har07
– har07

2015-08-24 13:25:53 +00:00
Commented Aug 24, 2015 at 13:25 — har07
– har07, Commented Aug 24, 2015 at 13:25

ThW · Accepted Answer · 2015-08-24 18:52:21Z

2

DOM can do this easily. DOMDocument::importNode() allows to import a node from another document. The imported node can be appended/inserted like any node.

DOMXpath::evaluate() can be used to fetch the nodes from a DOM.

$sourceXml = <<<'XML'
<processList>
  <process from="source">
    //some more child nodes
  </process>
</processList>
XML;    
$targetXml = <<<'XML'
<test>
  <processList>
    <process from="target">
      //some more child nodes
    </process>
  </processList>
</test>
XML;

$source = new DOMDocument();
$source->loadXml($sourceXml);
$sourceXpath = new DOMXPath($source);

$target = new DOMDocument();
$target->preserveWhiteSpace = false;
$target->formatOutput = true;
$target->loadXml($targetXml);
$targetXpath = new DOMXPath($target);

$targetNode = $targetXpath->evaluate('//processList[1]')->item(0);    
foreach ($sourceXpath->evaluate('//process') as $process) {
  $targetNode->appendChild(
    // import the node into the target document
    $target->importNode($process, TRUE)
  );
}    
echo $target->saveXml();

Output:

<?xml version="1.0"?>
<test>
  <processList>
    <process from="target">
      //some more child nodes
    </process>
    <process from="source">
    //some more child nodes
  </process>
  </processList>
</test>

edited Aug 24, 2015 at 18:52

answered Aug 24, 2015 at 14:25

ThW

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4 Comments

marius Over a year ago

Thanks for the answer! However I still dont see a reference. Destination should not be the output in this case. So what i wanted to achieve is to copy the process entries from source NEXT to the process entries of destination. In otherwords, I have both trees read in as SimpleXML and want to copy process nodes from SOURCE to DESTINATION

ThW Over a year ago

SimpleXML is an abstraction on top of the DOM, it has no nodes and no document - only SimpleXMLElement objects. This means that it is rather limited and can not copy nodes between documents. You need to use the DOM API directly.

marius Over a year ago

Okay that makes way more sense, but still simpleXMLelements contains the content itself no? If i echo it json_encoded i can see the content. So in theory it should be fine to move no? However I accept your answer and appreciate the fast solution. It was very helpful understanding how it works!

ThW Over a year ago

No, a JSON encoded SimpleXML object does not always contain all data from the original XML. Only for specific and simple documents.

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