TYPO3 Fluid ViewHelper to check if a partial name exists ("My/Partial")

PartialExistsViewHelper.php

<?php

namespace Krbu\Utility\ViewHelpers;

use TYPO3\CMS\Core\Utility\ExtensionManagementUtility;

/**
 * Copyright note: Some parts are copied from the Fluid package.
 * Usage example:
 *  <f:if condition="{krbu:PartialExists(partial: 'Category/{item.category.id}/DetailCol1')}">
 *    <f:then><f:render partial="Category/{item.category.id}/DetailCol1" arguments="{_all}" /></f:then>
 *    <f:else><f:render partial="Category/Default/DetailCol1" arguments="{_all}" /></f:else>
 *  </f:if>
 */
class PartialExistsViewHelper extends \TYPO3\CMS\Fluid\Core\ViewHelper\AbstractViewHelper {
  /**
   * Pattern to be resolved for "@partialRoot" in the other patterns.
   * Following placeholders are supported:
   * - "@packageResourcesPath"
   *
   * @var string
   */
  protected $partialRootPathPattern = '@packageResourcesPath/Private/Partials';

  /**
   * Does the given partial exist?
   *
   * @author Arne-Kolja Bachstein
   * @param string $partial
   *
   * @return boolean
   */
  public function render($partial) {
    $actionRequest = $this->controllerContext->getRequest();
    $possibilities = array(str_replace(
      '@packageResourcesPath',
      ExtensionManagementUtility::extPath($actionRequest->getControllerExtensionKey()) . 'Resources/', $this->partialRootPathPattern)
    );

    foreach($possibilities as $p) {
      if (file_exists($p . "/".$partial.".html")) {
        return true;
      }
    }

    return false;
  }
}

?>