In extbase, how to access item by another value than uid - typo3

Question

In a custom extbase extension, I need to call a show action, passing it another value than uid (this is a continuation of Use other than primary key as RealURL id_field).
As the value "other than uid" is not resolved, it results in the exception http://wiki.typo3.org/Exception/CMS/1297759968
EDIT: here's the current working (but ugly) Controller code:
/**
* ItemController
*/
class ItemController extends \TYPO3\CMS\Extbase\Mvc\Controller\ActionController {
/**
* itemRepository
*
* #var \STUBR\Weiterbildung\Domain\Repository\ItemRepository
* #inject
*/
protected $itemRepository = NULL;
/**
* action list
*
* #return void
*/
public function listAction(\STUBR\Weiterbildung\Domain\Model\Item $item=null) {
if (!empty(\TYPO3\CMS\Core\Utility\GeneralUtility::_GET('tx_weiterbildung_pi1'))){
$this->forward('show');
}
$items = $this->itemRepository->findAll();
$this->view->assign('items', $items);
}
/**
* action show
*
* #param \STUBR\Weiterbildung\Domain\Model\Item $item
* #return void
*/
public function showAction(\STUBR\Weiterbildung\Domain\Model\Item $item=null) {
$tx_weiterbildung_pi1_get = \TYPO3\CMS\Core\Utility\GeneralUtility::_GET('tx_weiterbildung_pi1');
if (!empty($tx_weiterbildung_pi1_get)){
$dfid = intval($tx_weiterbildung_pi1_get['durchfuehrungId']);
}
$items = $this->itemRepository->findByDurchfuehrungId($dfid);
// helpful:
//\TYPO3\CMS\Extbase\Utility\DebuggerUtility::var_dump($item);
$this->view->assign('item', $items[0]);
}
}
PS here are the 5 lines that could be used in the Repository if the magical method wouldn't work:
//public function findByDurchfuehrungId($dfid) {
// $query = $this->createQuery();
// $query->matching($query->equals('durchfuehrungId', $dfid));
// return $query->execute();
//}

Answer 1

Yes, when you're using actions with model binding in param it will always look for object by field defined as ID - in our case it's always uid, but remember, that you do not need to bind model automatically, as you can retrive it yourself.
Most probably you remember, that some time ago I advised to use <f:link.page additionalParams="{originalUid:myObj.originalUid}"Click here</f:link.page> instead of <f:link.action...>
In that case your show action would look like this:
public function showAction() {
$item = $this->itemRepository->findByOriginalUid(intval(GeneralUtility::_GET('originalUid')));
$this->view->assign('item', $item);
}
Where findByOriginalUid should work magically without declaration, but even if it doesn't it's just matter of 5 lines in the repo ;)
Other sample
According to the code you pasted I'd use it rather like this, in this case listAction gets a role of dispatcher for whole plugin:
public function listAction() {
// access get param in array
$tx_weiterbildung_pi1_get = \TYPO3\CMS\Core\Utility\GeneralUtility::_GET('tx_weiterbildung_pi1');
$dfId = intval($tx_weiterbildung_pi1_get['durchfuehrungId']);
if ($dfId > 0) { // tx_weiterbildung_pi1 exists and is positive, that means you want to go to showAction
$item = $this->itemRepository->findByDurchfuehrungId($dfId);
if (!is_null($item)) { // Forward to showAction with found $item
$this->forward('show', null, null, array('item' => $item));
}else { // Or redirect to the view URL after excluding single item ID from GET params
$this->redirectToUri($this->uriBuilder->setArgumentsToBeExcludedFromQueryString(array('tx_weiterbildung_pi1'))->build());
}
}
// No `tx_weiterbildung_pi1` param, so it should be displayed as a listAction
$items = $this->itemRepository->findAll();
$this->view->assign('items', $items);
}
/**
* #param \STUBR\Weiterbildung\Domain\Model\Item $item
*/
public function showAction(\STUBR\Weiterbildung\Domain\Model\Item $item = null) {
$this->view->assign('item', $item);
}
Your finder should also getFirst() object if possible:
public function findByDurchfuehrungId($DfId) {
$query = $this->createQuery();
$query->matching($query->equals('durchfuehrungId', $DfId));
return $query->execute()->getFirst();
}