Finally, I solved this problem by using a custom ViewHelper, derived from GroupedBy ViewHelper, inspired from https://gist.github.com/daKmoR/1287203, and adapted for extbase.
Here is the complete code for the ViewHelper, located in MyExt/Classes/ViewHelpers/GropuedForDateTimeViewHelper.php
<?php
namespace vendorMyExtViewHelpers;
/* *
* This script belongs to the FLOW3 package "Fluid". *
* *
* It is free software; you can redistribute it and/or modify it under *
* the terms of the GNU Lesser General Public License as published by the *
* Free Software Foundation, either version 3 of the License, or (at your *
* option) any later version. *
* *
* This script is distributed in the hope that it will be useful, but *
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHAN- *
* TABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser *
* General Public License for more details. *
* *
* You should have received a copy of the GNU Lesser General Public *
* License along with the script. *
* If not, see http://www.gnu.org/licenses/lgpl.html *
* *
* The TYPO3 project - inspiring people to share! *
* */
/**
* Grouped loop view helper for Datetime values.
* Loops through the specified values
*
* = Examples =
*
* <code title="Simple">
* // $items = array(
* // array('name' => 'apple', 'start' => DateTimeObject[2011-10-13 00:15:00]),
* // array('name' => 'orange', 'start' => DateTimeObject[2011-12-01 00:10:00]),
* // array('name' => 'banana', 'start' => DateTimeObject[2008-05-24 00:40:00])
* // );
* <a:groupedForDateTime each="{items}" as="itemsByYear" groupBy="start" format="Y" groupKey="year">
* {year -> f:format.date(format: 'Y')}
* <f:for each="{itemsByYear}" as="item">
* {item.name}
* </f:for>
* </a:groupedForDateTime>
* </code>
*
* Output:
* 2011
* apple
* orange
* 2010
* banana
*
* @license http://www.gnu.org/licenses/lgpl.html GNU Lesser General Public License, version 3 or later
* @api
*/
class GroupedForDateTimeViewHelper extends TYPO3CMSFluidCoreViewHelperAbstractViewHelper {
/**
* Iterates through elements of $each and renders child nodes
*
* @param array $each The array or Tx_Extbase_Persistence_ObjectStorage to iterated over
* @param string $as The name of the iteration variable
* @param string $groupBy Group by this property
* @param string $groupKey The name of the variable to store the current group
* @param string $format The format for the datetime
* @param string $dateTimeKey The name of the variable to store the current datetime
* @throws TYPO3CMSFluidCoreViewHelperException
* @return string Rendered string
* @author Bastian Waidelich <[email protected]>
* @author Thomas Allmer <[email protected]>
* @api
*/
public function render($each, $as, $groupBy, $groupKey = 'groupKey', $format = '', $dateTimeKey = 'dateTimeKey') {
$output = '';
if ($each === NULL) {
return '';
}
if (is_object($each)) {
if (!$each instanceof Traversable) {
throw new TYPO3CMSFluidCoreViewHelperException('GroupedForViewHelper only supports arrays and objects implementing Traversable interface' , 1253108907);
}
$each = iterator_to_array($each);
}
$groups = $this->groupElements($each, $groupBy, $format);
foreach ($groups['values'] as $currentGroupIndex => $group) {
$this->templateVariableContainer->add($groupKey, $groups['keys'][$currentGroupIndex]);
$this->templateVariableContainer->add($dateTimeKey, $groups['dateTimeKeys'][$currentGroupIndex]);
$this->templateVariableContainer->add($as, $group);
$output .= $this->renderChildren();
$this->templateVariableContainer->remove($groupKey);
$this->templateVariableContainer->remove($dateTimeKey);
$this->templateVariableContainer->remove($as);
}
return $output;
}
/**
* Groups the given array by the specified groupBy property and format for the datetime.
*
* @param array $elements The array / traversable object to be grouped
* @param string $groupBy Group by this property
* @param string $format The format for the datetime
* @throws TYPO3CMSFluidCoreViewHelperException
* @return array The grouped array in the form array('keys' => array('key1' => [key1value], 'key2' => [key2value], ...), 'values' => array('key1' => array([key1value] => [element1]), ...), ...)
* @author Bastian Waidelich <[email protected]>
*/
protected function groupElements(array $elements, $groupBy, $format) {
$groups = array('keys' => array(), 'values' => array());
foreach ($elements as $key => $value) {
if (is_array($value)) {
$currentGroupIndex = isset($value[$groupBy]) ? $value[$groupBy] : NULL;
} elseif (is_object($value)) {
$currentGroupIndex = TYPO3CMSExtbaseReflectionObjectAccess::getPropertyPath($value, $groupBy);
} else {
throw new TYPO3CMSFluidCoreViewHelperException('GroupedForViewHelper only supports multi-dimensional arrays and objects' , 1253120365);
}
if (strpos($format, '%') !== FALSE) {
$formatedDatetime = strftime($format, $currentGroupIndex->format('U'));
} else {
$formatedDatetime = $currentGroupIndex->format($format);
}
$groups['dateTimeKeys'][$formatedDatetime] = $currentGroupIndex;
if (strpos($format, '%') !== FALSE) {
$currentGroupIndex = strftime($format, $currentGroupIndex->format('U'));
} else {
$currentGroupIndex = $currentGroupIndex->format($format);
}
$currentGroupKeyValue = $currentGroupIndex;
if (is_object($currentGroupIndex)) {
$currentGroupIndex = spl_object_hash($currentGroupIndex);
}
$groups['keys'][$currentGroupIndex] = $currentGroupKeyValue;
$groups['values'][$currentGroupIndex][$key] = $value;
}
return $groups;
}
}
?>
And here is an example of a template using it:
{namespace m=vendorMyExtViewHelpers}
<f:layout name="Default" />
<f:section name="main">
<m:groupedForDateTime each="{myitems}" as="myitemsyear" groupBy="date" format="%Y" groupKey="year" dateTimeKey="yearKey">
<h2>{year}</h2>
<m:groupedForDateTime each="{myitemsyear}" as="myitemsmonth" groupBy="date" format="%B" groupKey="month" dateTimeKey="monthKey">
<h3>{month}</h3>
<ul>
<f:for each="{myitemsmonth}" as="myitem">
<li>{myitem}</li>
</f:for>
</ul>
</m:groupedForDateTime>
</m:groupedForDateTime>
</f:section>
