A Fluid ViewHelper to fall back to a default value in case a variable is empty.

DefaultViewHelper.php

<?php
namespace Api\Core\ViewHelpers;

/*                                                                        *
 * This script belongs to the TYPO3 Flow package "Api.Core".              *
 *                                                                        *
 *                                                                        */

use TYPO3\Flow\Annotations as Flow;

/**
 *
 * @Flow\Scope("prototype")
 */
class DefaultViewHelper extends \TYPO3\Fluid\Core\ViewHelper\AbstractViewHelper {

	/**
	 * Get the header include code for including Twitter Bootstrap on a page. If needed
	 * the jQuery library can be included, too.
	 *
	 * Example usage:
	 * {namespace a=Api\Core\ViewHelpers}
	 * {foo -> a:defaultValue('')>
	 *
	 * @param string $default
	 * @param string $content
	 * @return string
	 */
	public function render($default, $content = NULL) {
		if ($content === NULL) {
			$content = $this->renderChildren();
			if ($content === NULL || $content === '') {
				return $default;
			}
		}
		return $content;
	}

}

?>

Can be used like this:

{setup.validTo -> f:format.date() -> a:default(default: 'unlimited')}