Compare SimpleXml Object

Question

I'm trying to compare two SimpleXML Objects.

One is fetched from DB and the other one from a XML API, but the result is always false, whether the XML are in fact identical or not.

What am I doing wrong?

$objDbXml   = simplexml_load_string($objReisen->xml); // XML from DB           
$objApiXml  = simplexml_load_string(getXMlFromApi()); // XML from Api
var_dump($objDbXml->Reise->Z_LEISTUNGEN == $objApiXml->Reise->Z_LEISTUNGEN);
// Result is always false

The output of var_dump($objDbXml->Reise->Z_LEISTUNGEN , $objApiXml->Reise->Z_LEISTUNGEN):

object(SimpleXMLElement) #69 (1) {
    ["TextLine"]= > array(11) {
        [0] = > string(43) "Erlebnisreise mit hÃ¶chstens 13 Teilnehmern" 
        [1] = > string(39) "DurchfÃ¼hrungsgarantie ab 4 Teilnehmern" 
        [2] = > string(127) "Linienflug mit South African Airways von Frankfurt a.M. nach Kapstadt und zurÃ¼ck von Port Elizabeth (von MÃ¼nchen auf Anfrage)" 
        [3] = > string(28) "Reiseminibus mit Klimaanlage" 
        [4] = > string(111) "Ãœbernachtungen in Hotels und Lodges sowie 2 Ãœbernachtungen in einer exklusiven Lodge imÂ Kariega Game Reserve" 
        [5] = > string(67) "TÃ¤glich FrÃ¼hstÃ¼ck, 2 x Mittagessen,Â 4 x Abendessen, 1 Weinprobe" 
        [6] = > string(123) "1 Safari im Addo-Elephant-NP;Â 2 Safaris im offenen GelÃ¤ndewagen, 1 Wandersafari und 1 BootsfahrtÂ im Kariega Game Reserve" 
        [7] = > string(41) "NationalparkgebÃ¼hren und Eintrittsgelder"
        [8] = > string(14) "Reiseliteratur" 
        [9] = > string(43) "Zertifikat Ã¼ber 100 mÂ² Regenwald fÃ¼r Sie" 
        [10] = > string(42) "Deutsch sprechende ChamÃ¤leon-Reiseleitung"
    }
}

object(SimpleXMLElement) #67 (1) {
    ["TextLine"]= > array(11)
    {
        [0] = > string(43) "Erlebnisreise mit hÃ¶chstens 12 Teilnehmern" 
        [1] = > string(39) "DurchfÃ¼hrungsgarantie ab 4 Teilnehmern" 
        [2] = > string(127) "Linienflug mit South African Airways von Frankfurt a.M. nach Kapstadt und zurÃ¼ck von Port Elizabeth (von MÃ¼nchen auf Anfrage)" 
        [3] = > string(28) "Reiseminibus mit Klimaanlage" 
        [4] = > string(111) "Ãœbernachtungen in Hotels und Lodges sowie 2 Ãœbernachtungen in einer exklusiven Lodge imÂ Kariega Game Reserve" 
        [5] = > string(67) "TÃ¤glich FrÃ¼hstÃ¼ck, 2 x Mittagessen,Â 4 x Abendessen, 1 Weinprobe" 
        [6] = > string(123) "1 Safari im Addo-Elephant-NP;Â 2 Safaris im offenen GelÃ¤ndewagen, 1 Wandersafari und 1 BootsfahrtÂ im Kariega Game Reserve" 
        [7] = > string(41) "NationalparkgebÃ¼hren und Eintrittsgelder" 
        [8] = > string(14) "Reiseliteratur" 
        [9] = > string(43) "Zertifikat Ã¼ber 100 mÂ² Regenwald fÃ¼r Sie" 
        [10] = > string(42) "Deutsch sprechende ChamÃ¤leon-Reiseleitung"
    }
}

what does `var_dump($objDbXml->Reise->Z_LEISTUNGEN, $objApiXml->Reise->Z_LEISTUNGEN);` outputs ? — Prix, Jul 29 '13 at 22:14
You can't match a vardump as it's not in the memory. You might want to match XML as the plain string before you store it into an XML object, unless you want to loop through the object to match it against the other one. — Ben Ashton, Jul 29 '13 at 22:23
@BenAshton A complete String comparison is not an option because i have to detect which elements differ. — lasagne, Jul 30 '13 at 07:29
@Prix The output is always false. Whether the XML are equal or not. — lasagne, Jul 30 '13 at 07:30
@lasagne my code is different then yours, I just want to know the results of it to know how to best deal with your data. — Prix, Jul 30 '13 at 07:36
@Prix: Sorry my fault. Here is the dump: [http://snipt.org/ARgg3](http://snipt.org/ARgg3) — lasagne, Jul 30 '13 at 08:44
possible duplicate of [PHP - Check if two arrays are equal](http://stackoverflow.com/a/5678990/342740) — Prix, Jul 30 '13 at 09:10
If I use the identity operator === as mentioned in the post above I still get false whether xml are euqal or not. — lasagne, Jul 30 '13 at 09:39
Perhaps this can help? http://php.net/manual/en/language.oop5.object-comparison.php you want to compare an object, not an array. — Ben Ashton, Jul 30 '13 at 17:19

score 12 · Accepted Answer · answered Jul 30 '13 at 17:45

The problem here, as so often with SimpleXML, is in the fact that a SimpleXMLElement is not a "normal" PHP object. SimpleXML is not a parser which spits out fully-formed PHP objects with properties and methods, but a "live" API linked to an internal representation of an XML document.

The manual page on Comparing Objects states that "Two object instances are equal if they have the same attributes and values, and are instances of the same class." When you run print_r() or var_dump() over a SimpleXMLElement it appears to have properties representing the child nodes and attributes, which would be the same for two objects built from identical XML. However, the actual implementation contains only a pointer into a memory structure created when the XML was parsed, which will be different even if you parse the same string twice. Thus simply comparing two SimpleXMLElement objects with == will never return true.

The actual solution depends on what exactly you want to compare:

if you want to see if a particular fragment of the XML is 100% identical between the two documents, you could use ->asXML() to get an XML string for that part of the document; e.g. $objDbXml->Reise->Z_LEISTUNGEN->asXML() == $objApiXml->Reise->Z_LEISTUNGEN->asXML()
if there are a few specific properties which you want to compare, you may be better off selecting those out and comparing them individually, so that the test returns true even if they appear in a slightly different order, or with special characters encoded slightly differently

Good answer. IIRC I think that the comparison of a SimpleXMLElement also checks if it's from the same document with `==` comparison and `===` comparison somewhat doesn't work at all like in normal PHP. — hakre, Apr 18 '15 at 07:52
Comparing two SimpleXMLElement objects with `==` *can* return `true` if it's actually the same element. When I iterate over `$node->xpath('../'.$node->getName())`, one of the elements tests positive `==$node` (but not `===$node`). This only works in the default namespace. — Black Mantha, Jan 16 '18 at 16:56

score 2 · Answer 2 · answered Mar 11 '17 at 16:14

The opensource TurboCommons library contains a class called XMLUtils which contains a powerful xml comparison method called isEqualTo().

With it, you can check if two xml strings or simplexml elements are equal or not, even if their elements and attributes have different order.

https://github.com/edertone/TurboCommons

To use it, download the phar file and import it to your project.

A simple example of how it works:

use org\turbocommons\src\main\php\utils\XmlUtils;

XmlUtils::isEqualTo('<root><a/></root>', '<root><a></a></root>');

// Returns true

XmlUtils::isEqualTo('<root><a/></root>', '<raat><a/></raat>');

// Returns false

Compare SimpleXml Object

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