TYPO3 Extbase how to empty ObjectStorage - typo3

Question

I want to "empty" an ObjectStorage when updating a Object:
It's TYPO3 4.6 with a Extbase Extension which allows you to show/add/edit/delete datasets in the frontend. At first sight everything looks good.
I have one field referencing another table:
TCA:
'partner' => array(
'exclude' => 0,
'label' => 'LLL:EXT:toco3_marketingdb/Resources/Private/Language/locallang_db.xlf:tx_toco3marketingdb_domain_model_firma.partner',
'config' => array(
'type' => 'select',
'size' => 5,
'foreign_table' => 'tx_toco3marketingdb_domain_model_partner',
'foreign_table_where' => 'ORDER BY tx_toco3marketingdb_domain_model_partner.partnerpkey',
'minitems' => 0,
'maxitems' => 20,
),
),
Model:
/**
* Partner
*
* #var Tx_Extbase_Persistence_ObjectStorage<Tx_Toco3Marketingdb_Domain_Model_Partner>
* #lazy
*/
protected $partner;
/**
* Sets the partner
*
* #param Tx_Extbase_Persistence_ObjectStorage<Tx_Toco3Marketingdb_Domain_Model_Partner> $partner
* #return void
*/
public function setPartner(Tx_Extbase_Persistence_ObjectStorage $partner) {
$this->partner = $partner;
}
Controller:
$partner = new Tx_Extbase_Persistence_ObjectStorage();
if (count($partnerarr) > 0){
foreach($partnerarr as $p){
$partner->attach( $this->partnerRepository->findByUid($p));
}
}
$organisation = $this->organisationRepository->findByUid($uid)
$organisation->setPartner($partner);
This is working as long there is an Object in the ObjectStorage. So I can add/delete/change relations. But when $partnerarr is empty an no objects get attached an empty Tx_Extbase_Persistence_ObjectStorage is assigned, the old values do not get "deleted". I also tried to assign null or "" but the an error occures because an ObjectStorage is needed. If I assign the empty ObjectStorage I don't get an error, but the old values still maintain :(
Any idea?
Thank you
Christian

Answer 1

Call the detach or removeAll methods to remove certain or all objects of the storage.
/** #var \Tx_Extbase_Persistence_ObjectStorage $organisationPartners */
$organisationPartners = $organisation->getPartner();
foreach ($organisationPartners as $partner) {
$organisationPartners->detach($partner);
}

Answer 2

Thank you #Wolfgang for your message.
I added the following function to my model:
/**
* detach Partner
*
* #param Tx_Toco3Marketingdb_Domain_Model_Partner $partner
* #return void
*/
public function detachPartner($partner) {
$this->partner->detach($partner);
}
In the controller I added:
$persistanceManager = t3lib_div::makeInstance('Tx_Extbase_Persistence_Manager');
$organisation = $this->firmaRepository->findByUid($uid);
$organisationPartners = $organisation->getPartner();
foreach ($organisationPartners as $organisationPartner) {
$organisation->detachPartner($organisationPartner);
}
$persistanceManager->persistAll();
$organisation->setPartner($partner);
It is important to persist before setting the new (empty) value...