PHP xpath() undefined offset 0 but element exists // LARAVEL - php

Question

i am really having trouble getting this to work. xpath works fine in other functions in the same file. I am trying to get a specific item from the XML file, which works fine when i dd() it. But when i try to load the exact same code into a variable it prompts "undefined offset 0". I am working local with Laravel.
XML
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<idPkg:Graphic xmlns:idPkg="http://ns.adobe.com/AdobeInDesign/idml/1.0/packaging" DOMVersion="15.1">
<Color Self="Color/u2a64f" Model="Process" Space="RGB" ColorValue="204 204 204" />
</idPkg:Graphic>
PHP
function getColor($colorID){ //$colorID = Color/u2a64f
$xml= simplexml_load_file('/Resources/Graphic.xml');
$colorNode = $xml->xpath('//Color[#Self="'.$colorID.'"]');
dd($colorNode[0]->attributes()->ColorValue);
/* outputs:
SimpleXMLElement {#316 ▼
+"0": "204 204 204"
}
*/
$fillColor = $colorNode[0]->attributes()->ColorValue; // Line of error
/* outputs:
ErrorException (E_NOTICE)
Undefined offset: 0
*/
return $fillColor;
}
EDIT:
what i just found out: when i replace the variable in xpath with the content of the variable it works.
function getColor($colorID){ //$colorID = Color/u2a64f
$xml= simplexml_load_file('/Resources/Graphic.xml');
// doesnt work
$path = '//Color[#Self="'.$colorID.'"]';
// does work
$path = '//Color[#Self="Color/u2a64f"]';
$colorNode = $xml->xpath($path);
dd($colorNode[0]->attributes()->ColorValue);
/* outputs:
SimpleXMLElement {#316 ▼
+"0": "204 204 204"
}
*/
$fillColor = $colorNode[0]->attributes()->ColorValue; // Line of error
/* outputs:
ErrorException (E_NOTICE)
Undefined offset: 0
*/
return $fillColor;
}
i just cant get my head around it... I am glad for any hints or help!

Answer 1

Nevermind i found the solution myself.
After checking my code again i saw that sometimes some XML nodes dont have the attribute FillColor. So i checked my param first if it is set and then proceed to xpath.