How to parse XML - simplexml_load_string returns error "parser error : StartTag: invalid element name"

Question

I am trying to parse XML to array in my custom module in Magento 2.2.7. Community version (free)

I am loading Helper\Data through Block element and this is "working".

---

This is my Helper\Data.php

<?php

namespace Vendor\Categories\Helper;
use Magento\Framework\Serialize\SerializerInterface;

class Data extends \Magento\Framework\App\Helper\AbstractHelper
{

   private $xml2;
   private $xml; 

  public function __construct(SerializerInterface $serializer) {
    $this->serializer = $serializer;
    $this->xml2 = dirname(file_get_contents('import/kategorije-za-import.xml'));
    $this->xml = $this->serializer->unserialize($this->serializer->serialize(simplexml_load_string($this->xml2)));

  } // end of construct

  public function testing(){
    var_dump($this->xml);
  }

This outputs error in

[2019-02-16 10:27:51] main.CRITICAL: Warning: simplexml_load_string(): Entity: line 1414: parser error : StartTag: invalid element name in /home/user/public_html/app/code/Vendor/Categories/Helper/Data.php on line 19 [] []

XML file location is: \home\user\public_html\import\kategorije-za-import.xml

My xml file is:

<?xml version='1.0' encoding='UTF-8'?>
<NewDataSet>
  <Table>
    <CategoryID>1</CategoryID>
    <CategoryName>Hardware</CategoryName>
    <ParentCategoryID>0</ParentCategoryID>
  </Table>
  <Table>
    <CategoryID>2</CategoryID>
    <CategoryName>Paketi i bundle</CategoryName>
    <ParentCategoryID>1</ParentCategoryID>
  </Table>
  <Table>
    <CategoryID>3</CategoryID>
    <CategoryName>Matične ploče</CategoryName>
    <ParentCategoryID>1</ParentCategoryID>
  </Table>
  <Table>
    <CategoryID>4</CategoryID>
    <CategoryName>Intel</CategoryName>
    <ParentCategoryID>3</ParentCategoryID>
  </Table>
</NewDataSet>

---

I have tested this as a script outside Magento and XML file loads and parses as array.

What to do? :)

Answer 1

In the code you have put into your question you pass the wrong content to the method simplexml_load_string. $this->xml2contains the ouput of dirname() which can't contain the content of your xml file as string (the input simplexml_load_string expects). This code should do what you expect:

public function __construct(SerializerInterface $serializer) {
   $this->serializer = $serializer;
   //get the root directory of your Magento installation (I assume your import directory has been created in the root directory. 
   //If not you have to change that part. You may also hardcode the path for testing
   $objectManager = \Magento\Framework\App\ObjectManager::getInstance();
   $directoryList = $objectManager->get('\Magento\Framework\App\Filesystem\DirectoryList');
   $path = $directoryList->getPath(\Magento\Framework\App\Filesystem\DirectoryList::ROOT);
   $this->xml2 = file_get_contents($path .'/import/kategorije-za-import.xml');
   $this->xml = $this->serializer->unserialize($this->serializer->serialize(simplexml_load_string($this->xml2)));

} // end of construct

I hope that helps.