Bug #52858 [Com]: dom_import_simplexml() doesn't work on newly created SimpleXMLElement nodes

From: Date: Wed, 13 Feb 2013 11:58:47 +0000
Subject: Bug #52858 [Com]: dom_import_simplexml() doesn't work on newly created SimpleXMLElement nodes
References: 1  Groups: php.bugs 
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Edit report at https://bugs.php.net/bug.php?id=52858&edit=1

 ID:                 52858
 Comment by:         hanskrentel at yahoo dot de
 Reported by:        tatarynowicz at gmail dot com
 Summary:            dom_import_simplexml() doesn't work on newly created
                     SimpleXMLElement nodes
 Status:             Open
 Type:               Bug
 Package:            SimpleXML related
 Operating System:   Windows 7
 PHP Version:        5.3.3
 Block user comment: N
 Private report:     N

 New Comment:

Please compare what you do with:

     $xml->three->addChild('alpha');

You will get a warning:

Warning: SimpleXMLElement::addChild(): Cannot add child. Parent is not a permanent member of the XML
tree

If you extend from SompleXMLElement you probably want to add a similar warning for your function.
You can check for the condition this way:

    if ($this[0] == NULL) {
        $where = __CLASS__ . '::' . __FUNCTION__ . '(): ';
        $what  = 'Cannot add child. Parent is not a permanent member of the XML tree';
        trigger_error($where . $what, E_USER_WARNING);
        return;
    }

I hope this is helpful and makes the bigger picture more clear that this is how SimpleXMLElement
works.

You can however create your own type that does know how to add this on the fly, however due to the
magic nature of SimpleXMLElement, it is not possible as long as you extend from 
SimpleXMLElement. 
It requires you to create a decorator and write code for that part of the magic your own and
delegate the rest to the SimpleXMLElement decoratee / subject.


Previous Comments:
------------------------------------------------------------------------
[2010-09-16 05:51:22] tatarynowicz at gmail dot com

Description:
------------
The problem is readily apparent when you run the test script. When 
SimpleXMLElement dynamically creates a child element, and you directly call a 
method on the child element, the $this context is apparently not a proper 
SimpleXMLElement, i.e. dom_import_simplexml() does not accept it as input.

class MyXML extends SimpleXMLElement {
    public function cdata($text) {
        dom_import_simplexml($this);
    }
}

$xml = new MyXML('<foo/>');
$xml->three->cdata('Three');

Test script:
---------------
<?php

class MyXML extends SimpleXMLElement {
    public function cdata($text) {
        $node = dom_import_simplexml($this);
        $owner = $node->ownerDocument;
        $node->appendChild($owner->createCDATASection($text));
        return $this;
    }
}

$xml = new MyXML('<foo/>');

// works
$xml->one = 'One';

// also works
$xml->two = '';
$xml->two->cdata('Two');

// doesn't work
$xml->three->cdata('Three');

print $xml->asXML();

Expected result:
----------------
<?xml version="1.0"?>
<foo><one>One</one><two><![CDATA[Two]]></two><three><![CDATA[Three]]></three></foo
>

Actual result:
--------------
Warning: dom_import_simplexml(): Invalid Nodetype to import in 
C:\WWW\Work\WC\www\dom.php on line 5

Notice: Trying to get property of non-object in C:\WWW\Work\WC\www\dom.php on line 
6

Fatal error: Call to a member function appendChild() on a non-object in 
C:\WWW\Work\WC\www\dom.php on line 7


------------------------------------------------------------------------



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Edit this bug report at https://bugs.php.net/bug.php?id=52858&edit=1


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