Remove all objects from a mn relation / objectstorage

gistfile1.txt

/**
   * action update
	 *
	 * @param Tx_Hcbookings_Domain_Model_Item
	 * @dontverifyrequesthash
	 * @return void
	 */
	public function updateAction(Tx_Hcbookings_Domain_Model_Item $item) {
		
		// Empty storage if no got submitted by form / last one has been removed
		// Remember, if you use this action on a form that doesnt contain all the availabilityRanges 
		// we need to bind the condition to an "indicator" field and not to "if form contains this elements"
		$formItem = $this->request->getArgument('item');
		if(!array_key_exists('availabilityRanges', $formItem)) {
			$storage = $item->getAvailabilityRanges();
			$storage->removeAll(clone $storage);
		}
		
		$this->itemRepository->update($item);
		$this->flashMessageContainer->add('Your Item was updated.');
		$this->redirect('show', null, null, array('item'=>$item));

	}