Splits a large XML file with many elements into individual XML files per element using PHP and DOMDocument

split-xml.php

<?php
/**
 * Splits a large XML file with many elements into individual XML files per element using PHP and DOMDocument
 * 
 * The script does the following:
 * - Load original XML
 * - Create template XML and remove elements
 * - For each element of the original XML
 *   - Create a clone of the template XML
 *   - Add element of the original XML to the clone
 *   - Update other nodes of the clone
 *   - Save clone
 */  

// create source
$source = new DOMDocument;
$source->preserveWhiteSpace = false;
$source->load('xml-input.xml');

// create template without items
$template = $source->cloneNode(true);
foreach (iterator_to_array($template->getElementsByTagName('item')) as $item) {
    $item->parentNode->removeChild($item);
}

// create separate xml for each item
foreach ($source->getElementsByTagName('item') as $index => $item) {
    $chunk = $template->cloneNode(true);
    $chunk->formatOutput = true;
    $newItem = $chunk->importNode($item, true);
    $chunk->getElementsByTagName('items')->item(0)->appendChild($newItem);
    $chunk->getElementsByTagName('title')->item(0)->nodeValue = 'XML with one item';
    $chunk->getElementsByTagName('counter')->item(0)->nodeValue = '1';
    $chunk->save('xml-output-' . ($index + 1) . '.xml');
}

xml-input.xml

<?xml version="1.0" encoding="UTF-8"?>
<root>
    <title>XML with three items</title>
    <items>
        <item>
            <id>1</id>
            <name>Item One</name>
        </item>
        <item>
            <id>2</id>
            <name>Item Two</name>
        </item>
        <item>
            <id>3</id>
            <name>Item Three</name>
        </item>              
    </items>
    <counter>3</counter>
</root>

xml-output.xml

<!-- xml-output-1.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<root>
  <title>XML with one item</title>
  <items>
    <item>
      <id>1</id>
      <name>Item One</name>
    </item>
  </items>
  <counter>1</counter>
</root>

<!-- xml-output-2.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<root>
  <title>XML with one item</title>
  <items>
    <item>
      <id>2</id>
      <name>Item Two</name>
    </item>
  </items>
  <counter>1</counter>
</root>

<!-- xml-output-3.xml -->
<?xml version="1.0" encoding="UTF-8"?>
<root>
  <title>XML with one item</title>
  <items>
    <item>
      <id>3</id>
      <name>Item Three</name>
    </item>
  </items>
  <counter>1</counter>
</root>