如何在Intershop7中注册ORMObjectListener

Question

We have implemented several custom ORM objects in our webshop implementation that have references (dependencies) to Intershop Product system object.

When a user tries to delete a certain product in back-office, it causes problems because references to that product may still exist in our custom objects. Naturally, deleting a product that is referenced from one of our custom objects generates an exception like this:

java.sql.SQLTransactionRollbackException: ORA-02091: transaction rolled back ORA-02292: integrity constraint (INTERSHOP.A1POSTPAIDPRICE_CO_002) violated - child record found  

We have figured that we could solve that by implementing an ORMObjectListener and overriding objectDeleting method to delete all the references before the product actually gets deleted.

Intershop cookbook for ORM layer states:

"Instances must implement the interface ORMObjectListener for a given ORM object type and register at the factory. The listener is called when instances of the given type are created, changed or removed."

( https://support.intershop.com/kb/index.php/Display/2G3270#Cookbook-ORMLayer-Recipe:NotificationofPersistentObjectChanges )

However, we cannot find a cookbook for registering the listener at the factory. What do we need to do to register the listener?

Also, if there is some better way for handling dependencies to system objects on our custom objects during delete event, I'm open to suggestions.

UPDATE:

This is the listener class I have tried with so far:

public class ProductDeleteListener implements ORMObjectListener<ProductPO> {

  @Inject
  ProductPOFactory productPOFactory;

  /** The Constant LOGGER. */
  private static final Logger LOGGER = LoggerFactory.getLogger(ProductDeleteListener.class);

  public ProductDeleteListener() {
    productPOFactory.addObjectListener(this, new AttributeDescription[0]);
  }

  @Override
  public boolean isOldStateNeeded() {
    // TODO Auto-generated method stub
    return false;
  }

  @Override
  public void objectChanged(ProductPO object, Map<AttributeDescription, Object> previousValues) {
    if (LOGGER.isDebugEnabled()) {
      LOGGER.debug("PRODUCT LISTENER TEST - CHANGE");
    }

  }

  @Override
  public void objectChanging(ProductPO object, Map<AttributeDescription, Object> previousValues) {
    // TODO Auto-generated method stub

  }

  @Override
  public void objectCreated(ProductPO object) {
    // TODO Auto-generated method stub

  }

  @Override
  public void objectCreating(ProductPO object) {
    // TODO Auto-generated method stub

  }

  @Override
  public void objectDeleted(ORMObjectKey objectKey) {
    // TODO Auto-generated method stub

  }

  @Override
  public void objectDeleting(ProductPO object) {
    if (LOGGER.isDebugEnabled()) {
      LOGGER.debug("PRODUCT LISTENER TEST - PRE DELETE");
    }

  }

}

But it is not working. Nothing gets logged when object changes or gets deleted.

Answer 1

In addition to what Willem Evertse wrote you need to place your registration code in a class that gets instantiated via Intershop Component Framework.

implementation.component:

<components xmlns="http://www.intershop.de/component/2010" scope="global">
<implementation name="ProductDeleteListenerRegistrar"
    class="your.fullqualifed.ProductDeleteRegistrar" start="start" stop="stop"></implementation>

instances.component:

<components xmlns="http://www.intershop.de/component/2010"> <instance name="ORMValidator" with="ORMValidator" scope="global"/></components>

You need to write a class, eg ProductDeleteRegistrar and provide start method in which you can add registration calls like Willem described. As for stop method you need to safely unregister your object listener. Make sure both methods are declared to be synchronized.

Answer 2

I think registering a listen would be the right approach. Maybe just look out for performance problems.

You are right that there are no examples of this, but here is an example. Get the factory that you want to receive messages from. In your case, it is ProductPOFactory

ProductPOFactory productFactory = (ProductPOFactory) NamingMgr.getInstance().lookupFactory(ProductPO.class);
productFactory.addObjectListener(new MyProductChangeListener());

MyProductChangeListener needs to extend AbstractORMObjectListener<ProductPO> and implement the method public void objectDeleting(T object)

Every time a product gets deleted your listener should be called and then you can clean up your custom orm objects. You can have a look at ImageSetDefinitionPOListener as an example