append XML tree as child to another XML, using PHP

Question

I want to add an XML tree into another XML, and I have tried with following code which is not working:

<?php
$str1 = '<parent>
            <name>mrs smith</name>
         </parent>';

$xml1 = simplexml_load_string($str1);
print_r($xml1);

$str2 = '<tag>
             <child>child1</child>
             <age>3</age>
         </tag>';
$xml2 = simplexml_load_string($str2);
print_r($xml2);

$xml1->addChild($xml2);
print_r($xml1);
?>

Expect output XML:

<parent>
    <name>mrs smith</name>
    <tag>
    <child>child1</child>
    <age>3</age>
    </tag>
</parent>

Please assist me.

Answer 1

You can use DOMDocument::importNode

<?php 

$str2 = '<tag>
             <child>child1</child>
             <age>3</age>
         </tag>';

$str1 = '<parent>
            <name>mrs smith</name>
         </parent>';

$tagDoc = new DOMDocument;
$tagDoc->loadXML($str2);

$tagNode = $tagDoc->getElementsByTagName("tag")->item(0);
//echo $tagDoc->saveXML();

$newdoc = new DOMDocument;
$newdoc->loadXML($str1);

$node = $newdoc->importNode($tagNode, true);
$newdoc->documentElement->appendChild($node);

echo $newdoc->saveXML();die;