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Bug #46143 Serializing SimpleXML removes the root node; asXML on unserailized breaks
Submitted: 2008-09-21 11:37 UTC Modified: 2008-10-16 18:09 UTC
From: firehed at gmail dot com Assigned:
Status: Not a bug Package: SimpleXML related
PHP Version: 5.2.6 OS: OS X 10.5
Private report: No CVE-ID: None
View Developer Edit
 [2008-09-21 11:37 UTC] firehed at gmail dot com 
Description:
------------
If you serialize a SimpleXMLElement object, the root-level node is lost, causing the unserialize() event to issue a warning-level error (and creating an empty SimpleXMLElement object) and cause most other SimpleXMLElement methods to fail with a warning-level error.

Reproduce code:
---------------
<?php
$xml = new SimpleXMLElement('<test><foo>1</foo><bar>2</bar></test>');
$serialized = serialize($xml);
$unserialized = unserialize($serialized);
$unserialized->addChild('testing', 'worked');
echo $unserialized->asXML();

Expected result:
----------------
<?xml version="1.0"?>
<test><foo>1</foo><bar>2</bar><testing>worked</testing></test>

Actual result:
--------------
Warning: unserialize() [function.unserialize]: Node no longer exists in /Applications/MAMP/htdocs/serialxml.php on line 4

Warning: SimpleXMLElement::addChild() [function.SimpleXMLElement-addChild]: Node no longer exists in /Applications/MAMP/htdocs/serialxml.php on line 5

Warning: SimpleXMLElement::addChild() [function.SimpleXMLElement-addChild]: Cannot add child. Parent is not a permanent member of the XML tree in /Applications/MAMP/htdocs/serialxml.php on line 5

Warning: SimpleXMLElement::asXML() [function.SimpleXMLElement-asXML]: Node no longer exists in /Applications/MAMP/htdocs/serialxml.php on line 6

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 [2008-09-21 15:12 UTC] phpwnd at gmail dot com 
AFAIK, you cannot serialize a SimpleXMLElement, because it's a resource wrapped inside an object and it would be impossible de restore that resource upon unserialize()-ation. That's why you receive an error: the unserialized object doesn't know where's the original document anymore. Store it in text form instead (asXML()).

Proposed solution #1: prevent SimpleXMLElement serialization, or make it produce an E_NOTICE. The error message could advise the user to store SimpleXMLElements as XML strings instead.

Proposed solution #2: allow serialization, make the serialized representation store the XML as a string and recreate the [copy of the original] document upon deserialization.
 [2008-10-16 18:09 UTC] rrichards@php.net 
Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

For reasons as stated by phpwnd
 [2011-04-29 13:50 UTC] MartinWillms2000 at aol dot com 
I have the same problem when using simplexml and reading a string entry from a 
node. The node contents is the following:

/mtdata/usb/data

I use the following code to read the node contents into a variable:

$temp_str = $xmlJobFile_cl->recording->target_directory;

Using this code the problem described above occurs. Therefore I think that the 
simplexml node is serialised to $temp_str. Applying a type cast to string 
solved the problem:

$temp_str = (string) $xmlJobFile_cl->recording->target_directory;

>php-config --version
5.2.6

>apache2ctl -v
Server version: Apache/2.2.3
Server built:   Sep 25 2008 11:25:06
 
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